OXFORD UNIVERSITY PRESS
Journal ofSemantics 7:121-141
© N.I.S. Foundation (1990)
Primary Perceptual Space and Inhere...
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OXFORD UNIVERSITY PRESS
Journal ofSemantics 7:121-141
© N.I.S. Foundation (1990)
Primary Perceptual Space and Inherent Proportion Schema: Two Interacting Categorization Grids Underlying the Conceptualization of Spatial Objects* EWALD LANG University ofWuppertal
Abstract
Perceptual Space and Inherent Proportion Schema.
Offering an analysis which draws on linguistic theorizing, the paper is meant as an invitation to psycholinguists and psychologists for discussion and cooperation.
INTRODUCTION With remarkable consistency all languages appear to have a certain sample of lexical items to make reference to spatial dimensions such as height, length, width, depth, distance, and thickness. Though there are some differences as to how language structures space (comparing, say, English with Hungarian or Japanese), the lexical field referring to spatial dimensional designation is in any case richer and more complex than would be needed simply to provide distinct labels for the three axes of a Cartesian system of coordinates. No doubt, there is a lot more to dimensional designation than mere discrimination of spatial coordinates. What is it? And why? And whence are we to derive the almost invariant pattern we observe across languages? One obvious source of this universality is its origin in human perceptual capacities. There is a considerable amount of research work on space perception, shape recognition, visual discrimination etc. which attempts to prove or at least to support the claim: The dimensions languages pick out are just those dimensions the human perceptual apparatus is tuned to pick out' (cf. Clark 1973: Clark & Clark 1977).
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Within the realms of cognitive studies, spatial structure is one of the few domains where attempts to trace mental representations from the level of sensory input conditions through conceptual structure to their lexical and grammatical organization seem to be feasible and revealing. Presenting a linguist's approach to the meaning and use of spatial dimensional terms, the paper aims to demonstrate why and how the semantic analysis of these linguistic items has to be justified in terms of nonlinguistic conceptual structure formation, which in turn has to be shown to derive from categorized perceptual input. Regarding framework and approach, the paper supplements Manfred Bierwisch's recent article on Comparison inyS, 6: 1.57-93 and 2.101-146. As to substance, it is argued that the structure of conceptual knowledge of spatial objects can plausibly be modelled by means of object schemata which result from two interacting categorization grids called Primary
122 Primary Perceptual Space and Inherent Proportion Schema
Figure 1 (a) B is 80 cm long, 30 cm wide, and 30 cm thick (b) B is 80 cm wide, 30 cm deep, and 3 cm thick
Though one might argue that object B in setting II is distinctly perceived so that this is not a proper case of constancy in perceptual features, the example at any rate illustrates the decisive role of the contextual setting. The relevant point is that object B is distinctly conceptualized in tie two settings. (The fact that in EnglishB in (I) is a board, whereas in (II) it is a window-sill or window-ledge gives us an additional hint.) Now consider an example proving from the opposite perspective that dimensional designation and perceptual features are independent. There is a class of objects which are intrinsically specified regarding height or depth, no matter how they are shaped or where they are placed in a contextual setting. Thus a book or a tombstone has a fixed height and width determined by the intrinsic orientation of the inscription it contains. Certainly, the height assigned
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True as this may be, it cannot be the whole story. There is more to dimensional designation than perception-based categorizing of axes, planes, extensions, and shapes. One of the major arguments in favour of this view draws on the fact that constancy in the perceptual characteristics of a certain object does not necessarily imply constancy as to the designation of its spatial dimensions, and vice versa. Consider a board B sized 80 X 30 X 3 cm in the contextual settings I, II as shown in Figure 1. In (a) the board is conceived as a freely movable object, hence the dimensional designations assigned to it refer to its inherent shape or gestalt properties. In (b), however, the same object B is conceived as part of the window niche, hence it is assigned position properties determined by the surrounding macro-object, that is, the width and depth of the niche are transferred to the board replacing or specifying its inherent properties (except thickness).
E.Lang 123
1 SEMANTIC ANALYSIS: BACKGROUND ASSUMPTIONS An investigation into the meaning of linguistic expressions that claims to be more than a mere description of intuitively felt equivalences and differences cannot do without some theoretical framework of assumptions and guidelines. As the semantic structure of lexical items is accessible only by way of indirect hypothesizing, we need a set of general and specific assumptions that determine what questions may reasonably be asked regarding a given domain of observable phenomena, and we need a few methodological guidelines enabling us to abstract theoretically significant facts from empirically available data. The general assumptions adopted for the analysis at issue may be briefly outlined by the following three key words: (1) MODULARITY. Human cognitive behaviour is essentially based on structures and processes which are determined by the interaction of relatively autonomous systems and subsystems which we call 'modules' (in roughly the sense of Fodor 1983). The structure formation that underlines a behaviour instance V is the joint product of relatively autonomous, purposefully interacting modules M,,M 2 ,M 3 ...
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to a book can be traced back to a perceptual verticality feature. This feature, however, mediated by our writing system and reading habits, has lost its relationship with gravitation etc. and has become a defining function-based feature of the concept BOOK. (Henceforth concepts will be indicated by italicized small caps.) In a similar way this applies to all spatial objects with an intrinsic orientation or perspective, i.e. where originally perception-based features have turned into ingredients of the conceptual representation of such objects where they no longer reflect perceptual conditions on object identification, but functional conditions concerning the use of, or access to, the pertinent object. Examples like this make it sufficiendy clear that there is no direct short cut from perception to language. To put it more precisely, die conditions under which perceptual features are involved in defining linguistic expressions for dimensional designation are more complex and less direct than the perceptionist view quoted above suggests. What seems to be clear is that perceptual features enter the meaning of dimensional terms only via conceptualization, that is, the relationship between categories of space perception and linguistic terms referring to spatial structure is mediated by some relatively autonomous level of conceptual structure which represents our everyday knowledge of space and spatial relations. This is precisely the sort of mental representation which the semantic analysis presented below aims to shed some light on.
124 Primary Perceptual Space and Inherent Proportion Schema
(2) AUTONOMY. Each module M is defined by certain principles which determine a set of elementary units E and a set of rules R according to which the elements of E are combined to form structural representations SR A module is autonomous to precisely the extent to which E, R and/or SR are specific to M. (3) INTERACTION. Given some behaviour instance V, two modules M,, M2 interact iff, with respect to one and the same V, some SR, generated by M, contains variables or parameters which are instantiated by units of some SR generated by M2, or vice versa; otherwise, M, and M2 are structurally disconnected.
(4) (a) lang/kurz; dick/diinn; long/short; thick/thin; (b) hoch/niedrig; high/low; (c) weit/eng; wide, broad/narrow, tight; (d) grofi/klein
breit/schmal wide, broad/narrow tief/flach deep/flat, shallow weit/nah far/near, close
big, tall, large/small, short, little occurring in sentences having the grammatical structure (5): (5) x is m DA, ((and) n DA2 ((and) 0 DA3)) where x — subject noun phrase naming a spatial object m,n,o= optional measure phrases DA, 23 — distinct elements from the list in (4) we single out as an appropriate behaviour instance the semantic interpretation a sentence token s of (5) is assigned to with regard to some context ct. Further details are given below. As to the modules involved in the structure of this domain of linguistic knowledge, we posit the following systems and subsystems: (i) The system of grammatical knowledge G relating sound/graphic patterns to conceptual structures by means of representations which are determined by the interacting subsystems of phonological, syntactic, and semantic structure formation. Among the various components of G we will focus on the memory-based system of lexical knowledge LEX which specifies the set of basic (though internally complex structured) expressions of some language L, taking the items in (4) as an illustrative sample. (ii) The system of conceptual knowledge C which in view of its intermodal
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These somewhat abstract stipulations will immediately become more understandable when we fill in the more specific notions that are needed for the semantic analysis of spatial dimensional terms. Restricting the scope of material to the group of dimensional adjectives (DA) listed in (4):
E.Lang 125
accessibility serves as the representational mediator with regard to the other systems involved. Within C we will provisionally delimit some subsystem C ^ ^ which relates the structure of physical space to mental representations. Thus, Cspaa_ is construed as the conceptual module which determines the way in which spatial information, no matter whether sensory inputted or linguistically encoded, is processed. The semantic analysis of dimensional adjectives may thus serve as a peephole to look at the internal structure of C ^ ^ . (iii) The system of perceptual structureformation P, which also comprises various subsystems. Here we are interested only in the visual subsystem in its interaction with the motoric and kinaesthetic subsystems.
(6) coMPOsmoNAUTY. The semantic interpretation of a sentence is composed of the semantic contributions of its syntactically determined lexical, phrasal, and clausal constituents. Within the given scope of analysis, this principle will be relevant in specifying the contextual restrictions the conjoined DA impose upon each other within a sentence token of (5). (7) TWO-LEVEL APPROACH. The semantic interpretation of linguistic expressions involves a mapping between two separate, autonomous representations: (a) the level of Semantic Form (SF) which is determined by module G (b) the level of Conceptual Structure (CS) which is determined by module C The distinction between SF and CS marks one of the major points due to which the present approach to semantics differs from previous analyses, notably from research work treating the same lexical material within a semantic marker framework (cf. Bierwisch 1967; Hlebec 1983; Lafrenz 1983; Lehrer 1974; Lyons 1977 for genuine linguistic proposals; and cf. Harris & Morris 1986 and the references cited there to psycholinguistic studies which take the feature analysis proposed by Bierwisch 1967 as a basis for experimental research). (8) LEXICAL ENTRY OF DA. A lexical item comprises several sorts of structural information defining its entry as an element of LEX in specifying its relations to the other subsystems of G. Besides information regarding phonetic form and syntactic categorization, die entries for DAs contain a representation of their Semantic Form specifying the componential structure of their lexical meaning. Omitting technical details, all DAs meet the following schema: [[QUANT DIM x] - [v + c]]
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Having set up the basics thus far, we are now ready to add some specific assumptions concerning the semantic theory adopted here. Leaving out a lot of linguistic technicalities they may be briefly indicated by the following key words (for details see Bierwisch 1987,1988b, 1989; Lang 1987,1988,1989);
126 Primary Perceptual Space and Inherent Proportion Schema
QUANT is a semantic prime for a scaling operation which assigns a scale value composed of v. and c to some spatial object x with regard to a dimension d. The latter is represented here by the placeholder DIM, a variable to be instantiated by a limited set of constants (MAX, SUB, VERT, OBS, DIST...) which specify the dimensional meaning component of the items listed in (4) above. Some details on the nature and interpretation of these constants are given in section 3. Without retelling the whole story of the semantics of dimensional designation (which is elaborated at length in Lang 1987, 1989), we will focus here on two intertwined problems which might be of interest also outside the scope of linguistics proper, namely:
Put somewhat more technically, this amounts to the task of setting up a justified mapping relation between the two representations SF and CS as shown in Figure 2, which summarizes the assumptions outlined so far in an overall diagram.
SYNTAX + [Adj] PHONOLOGY
.IHOCHI
LEXICAL SEMANTICS (Semantic Form)
\
x3
xl
QL> ' SPACE
Figure 2 Semantic Form of DA as an interface between linguistic and conceptual structure
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(9) How are these meaning components obtained and justified? (10) What do they reveal about the way space perception is involved in the conceptualization of space?
E.Lang 127
2 SEMANTIC ANALYSIS: FACTS AND DATA T O BE COPED W I T H
( i l ) OBJECT GUESSING
x is long, wide, and high x is wide, deep, and high *x is wide, thick, and deep *x is deep and thick x is high/tall and thick x is long and thick
(x = TABLE, CHEST, ...) (x =• CUPBOARD, TUNNEL, CHEST) (no value for x found) (no value for x found) (x — TOWER, TREE, POLE) (x — POLE , ROPE ...)
Naming object extensions. In another task subjects were given pictures showing simple geometric figures in various positions. The figures were claimed to represent concrete spatial objects, say, a BRICK or a TOMBSTONE (cf. the cuboid shown in (12)) and the subjects had to name the extensions a, b, c by DA. As the data were collected from native speakers of German we quote the results in the original. Regarding this sample of data there is practically no difference between the German DAs and their English or French equivalents. The results of these tests were taken as a data base to subclassify a set of objects having the same shape into objects having either an intrinsic or a canonical orientation or no fixed orientation at all. Positioning objects. In a third test, resembling an acting-out task, subjects were given an identified object of fixed size, say, a BOOK or a BRICK, and they were asked to position the object according to its possible description by sentences like
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The first step of the analysis was to obtain a reliable data base with regard to the distribution of DA, that is, a sufficiently clear picture of which combination of DAs may apply to what type of spatial object, and which variation is allowed within a given combination. The data were, inter alia, obtained from native speakers in the course of three different eliciting tests, which are briefly described in (1 I)-(I 3) below. Object guessing. Subjects were presented with sentences like those listed in the left part of (11) and asked to replace x by an appropriate name of a spatial object. The results (indicated in the right part of (11)) show a remarkably constant pattern regarding combinations which can easily be filled with object names and combinations for which no suitable object names seem to be available. These asterisked combinations were taken as evidence for compatibility restrictions among the DA.
TOMB STONE
BRICK
B: Assignments
A: Positions
a — tief b — breit c — hoch a — hoch/lang b — breit c - dick
a — breit b — hoch c — tief a — breit b — hoch c-dick
a — hoch b — breit c — tief
a — hoch b — breit c - dick a — lang b — breit c — hoch
b-tief c — breit
a — hoch
a — hoch b-tief c — breit
a - tief b — hoch c — breit
a — tief b — hoch c — breit
b — hoch c — breit
a lang b — breit c — hoch
a — breit/lang b hoch c - dick
a — breit b-tief c — hoch
a — lang b breit c — hoch
a ~ lang
a — hoch b -??? c — breit
a — lang b — breit c — hoch
a — brett b — hoch c - dick
a — hoch b — breit c — dick
a - lang b — breit
a - lang b — breit
a - lang b - dick c — dick
a - lang b — breit c — dick
a - lang b — breit c — dick
VI
a - lang b — breit c — dick
v
VI
IV
A
Z7\
IV
m
ill
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3 a. o
3
a
o-
T3
I
3s
E.Lang 129
long wide high high (13) The brick is 24 cm • wide •, 11 cm- deep *long deep 'thick 'thick
and 7 cm
thick high wide wide 'long
(14) Out of 20 possible 3 term combinations there are only 10, 15 2 term 9, 6 1 term 1, which are/is interpretable as a suitable description of the dimensions of some object x. These combinatorial restrictions are indicative of the DIMENSIONALITY of the object to which a DA may be applied. We thus get the following conditions: (15) lang may be applied to iD, 2D, or 3D objects hoch, breit require a 2D or 3D object dick, weit, tief require a 3D object Moreover, the results in (14) allow us to state compatibility conditions within a DA-combination such as (16) dick, tief can never be combined lang, dick never designate the same object extent breit, weit can alternatively designate the same object extent etc. In addition to (14), we observe RESTRICTIONS ON VARIATION: (17) Within the 20 interpretable combinations of DAs, which arithmetically yield 78 possible variations, there are only 40 interpretable ones. Restrictions on variation indicate crucial aspects of OBJECT CATEGORIZATION. Take just two examples: (18) The distribution of hoch subdivides 3D objects into three subclasses of objects with respect to
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The curled brackets indicate the range of DA which may or may not (*) be applied to designate the pertinent object extent. Of course, each DA can occur only once within a 3-term combination. The aim of this test was to clarify the constraints imposed on variation within a given combination. The results indicate, among other things, the role of the relative extent of the various object axes in dimensional designation note the complemetary distribution of long and thick above. The data base emerging from these tests now allows us to formulate some clear-cut facts as to the combinatorial behaviour of DA. Thus, drawing on the six German DA lang, hoch, breit, weit, tief, dick (i.e. all of (4) exceptgrofi) it holds that
130 Primary Perceptual Space and Inherent Proportion Schema (a) canonical orientation (b) inherent orientation (c) being unspecified as to orientation (19) The distribution of tief subdivides 3D objects with respect to (a) canonical perspectivation (b) inherent perspectivation (c) being unspecified as to perspective
(TOWER, TREE) (BOOK, PICTURE) (BRICK, POLE)
objects into three subclasses of (RIVER, DITCH) (HOLE, WOUND) (BRICK, BOARD)
(20) Applying some DA to a spatial object is construed as (1) primary identification if the spatial properties to which lang, dick, hoch etc. refer are defining properties of the object and hence form part of its conceptual representation. The designation of an object extent by a DA is construed as (2) contextual specification if the spatial properties to which hoch, tief, breit refer are assignable, but not defining properties of the object, and hence do not form part of the conceptual representation of the object perse. Note the revealing cross-classification emerging from this distinction. It predicts that e.g. lang and dick, whenever applied, identify defining properties of an object, whereas hoch and tief will do so only if applied to objects having a canonical or intrinsic orientation and/or perspectivation. Contextual specification, on the other hand, is restricted to hoch and tief if they are applied to objects that are unspecified as to orientation/perspectivation. Thus, Der Tumi ist 20m hoch and Das Bild ist im hoch exemplify cases of primary identification, which, at the same time, rules out *Der Turm ist 20m lang as an acceptable sentence and provides for the suitable interpretation of Das Bild ist lmlang. Examples of contextual specification are DieStange ist 20m hoch or Der Tunnel ist 30m tief, which imply that the vertical orientation of the pole is induced by the contextual setting (i.e. its upright position) or that the tunnel is assigned depth from the perspective of a (potential) observer, which defines another type of contextual setting. The distinction noted in (20) is confirmed by the following valid (-•) or invalid (-A) entailments:
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Correlating the distinctions among objects noted in (18) and (19) with distributional facts deriving from (14) and (17), we obtain another important distinction. Actually, there are two ways in which to construe the designation of an object extension by a DA in accordance with the syntactic pattern given in (5):
E. Lang 131
(21) The pole is 20m high/tall The tower is 20m high/tall The milk pot is 30cm deep The desk is im deep
-» The pole is 20m long -h T h e tower is 20m long -• The milk pot is 30cm high /-* The desk is im high
(22) (a) flach (BUILDING, DITCH) (b) niedrig(poT) (c) hochfliegen (fly high)
: hoch (BUILDING), tief (DITCH) : hoch (POT), tief (POT) : tieffliegen (flylow), niedrigfliegen (fly low)
These facts (and others which I cannot go into here) are beyond the reach of any semantic feature analysis. In Lang 1987,1988,1989 it is shown how they might be accounted for by the rules mapping SF on to CS. To close the list of semantic facts a theory of dimensional designation has to cope with, I will discuss some TYPES OF CONTEXTUAL DETERMINATION involved in the interpretation of DAs. Consider the following sentence: (23) Das Brett ist breit genug, aber zu diinn The board is wide enough, but too thin The first type of contextual determination to note is the selectional relations holding between the DAs and the object they are assigned to. Thus, breit (wide) is applicable to objects like BOARD, but not to BALL or POLE. This indicates that it is a crucial property of spatial objects whether or not the relevant axes are disintegrated (as are the symmetry axes of cuboids) or integrated (as are the diameters of circles). Dick : diinn (thick : thin) designate a disintegrated axis if applied to BOARD, but refer to other properties if applied to POLE, SOUP or FOG. The second type of contextual determination we observe in (23) concerns the inherent relativity of breit : schmal (broad/wide : narrow). The point is that
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The valid entailments rest on the possibility of detaching contextually induced specifications without changing the defining properties of the object at issue. Facts like the ones sketched in (21) provide strong evidence for the differentiation of SF and CS also from a purely theoretical point of view. Entailment relations of this kind cannot be encoded in the semantic representations of the pertinent DA (one would either be forced to accept overspecified Semantic Forms or else to assume « -ways polysemy for hoch, tief, breit (high, deep, broad/ wide) both being untenable solutions), so these entailments have to be accounted for by the rules mapping the Semantic Form of these DAs onto the conceptual representation of the objects involved. There are, by the way, further puzzling semantic facts which clearly support an analysis in terms of separate representations. Take the phenomenon of socalled branching antonymies as indicated by the various oppositions marked by ':' of e.g. hoch:
132 Primary Perceptual Space and Inherent Proportion Schema
obviously there is no independent defining spatial property according to which breit: schmal is assigned to physical objects. The object extent d to which breit: schmal is assigned is determined in relation to some other object extent d' where d' is identifiable independently. Consider the way d and d' are selected by context in (24): (24)
(I)
(Ill)
(II)
i. d — a — breit d' — b — lang
d — b — breit d' — a — hoch
d — b — breit d' — a — tief
In short, the object axis designatable as breit is chosen in relation to some other object axis which is independently designated as either lang or hoch or tief. Hence, it is a specific feature of breit: schmal that it is assigned only by way of contextual specification (cf. (2o)(2) above), or, to put it the other way round, it is a revealing fact that there is no primary perceptual cue available for the assignment of breit : schmal, which in turn casts some doubt on all previous analysis which identify breit : schmal with horizontality. Again, the peculiarity of this pair of DA provides a striking argument in favour of the SF-CS distinction, and so does the third type of contextual determination to be noted here, namely, the mutual determination the conjoined DAs impose upon each other within a sentence. (25)
(I) Das Brett ist lang und breit genug, aber zu diinn (II) Das Brett ist breit und hoch genug, aber zu diinn (III) Das Brett ist breit und tief genug, aber zu diinn
What we observe is that, regarding the assignment of breit, the sentences in (2s)(I-IH) provide exactly the same contextual information as do the non-verbal contextual settings in (24) (I-III). This equivalence of situational and linguistic contextual information can only be formulated in terms of conceptual structure representation. Besides this, the partial equivalence of (24) and (25) provides a clear case of what it means to construe CS as an intermodally accessible level of representation. Summing up this section, we may draw the following conclusions. First, each DA has exactly one representation at SF level, but a range of interpretations on CS level. Second, this range of interpretations is determined by the conceptual module C^^ which organizes the way in which spatial objects are conceived.
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1/
L
RLang 133
Third, each spatial object x represents a certain ensemble of perceptually based and conceptually categorized properties. A subset of these properties are designated as spatial dimensions of x, that is, as gradable aspects of x which are at the same time relevant to human behaviour in a spatial environment. These are partial answers to the questions posed in (9) and (10) above. What we shall do next can now be narrowed down to the following questions: (26) What defines some x as a spatial object? (27) What are the dimensionable properties of x? (28) How are they to be represented on SF and CS?
3 SPECIFYING OBJECTS AS TO GESTALT AND POSITION Taking up the key words perceptually based and conceptually categorized, this section presents a precis of two chapters of Lang 1987, 1989 where the various criteria and conditions as well as the way they are assembled to form separate but interacting categorization grids are elaborated. Some x is defined as a spatial object by two interacting sets of principles which are provisionally called Inherent Proportion Schema (IPS) and Primary Perceptual Space (PPS). The former defines the dimensionable gestalt properties of a spatial object; the latter defines a system of axes within which the gestalt properties of objects can be interpreted as position properties. Take the by now familiar examples: (29) (a) The pole is 10m long
vs.
(b) The pole is 10m high.
Long makes reference to the (perceptually salient) maximal extension of an object (having a maximal axis is in any case a defining gestalt property); hence long here identifies the maximal extension of a given pole. High in (b) interprets this maximal extension of the pole in terms of verticality thus turning the gestalt property into a position property. Speaking in terms of conceptual structure, we can put it like this: Some object x is assigned a position property if a certain extension of x defined by IPS is redefined by being projected on to some axis of the external space as determined by PPS. This projection is a directed one, revealing the asymmetry in the interaction of IPS and PPS which explains why (b) entails (a), but not vice versa (cf. also (21) above). Now, after having briefly sketched what IPS and PPS are supposed to be, let us have a closer look at their internal structure. The device called IPS is
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With this in mind, we may now move over to the next section which outlines the notional components of a theory that attempts to answer (26)-(28).
134 Primary Perceptual Space and Inherent Proportion Schema
essentially based on categorizing visual input information according to a set of interacting principles. Without going into details (discussed at length in Lang 1987,1989), we have to assume principles which determine:
weit (in the sense of wide on the inside).
Obviously, there is some logical order within thefivecategorization steps (or levels) listed above: the first three lay the ground for any sort of dimensional designation, and are therefore presupposed by all DAs; the fourth and fifth yield more specific features that differentiate among the DAs. Taken together, (i)-(v) make up a categorization grid IPS which yields values and parameters that we need in order to come to grips with the semantics of dimensional designation, regarding both Semantic Form and CS representations. As to Semantic Form, IPS provides us with the three constants MAX, SUB, DIST which specify the dimensional meaning component of lang : kurz, dick : diinn, and weit : eng, respectively, in the way indicated in (8) above. They are construed as semantic primes representing a set of conditions to identify an object extension, or more technically in the sense of (3), as parameters on the SF level which are being fixed on the CS level, which specifies the range of object extensions instantiating the respective SF parameters. The CS representations providing die values which MAX, SUB, DIST can take are discussed in section 3.
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(i) OBJECT DELIMITATION—how the field of vision is analysed into discernible constant units which are defined by lines, edges, planes, and volumes. (ii) SYMMETRY AXES —how delimited objects are evaluated as to homogeneousness and orthogonality of their bounding surfaces in terms of the symmetry axes defining them. (Note that DAs pick out certain symmetry axes of an object x as reference extension.) (iii) AXIAL DISINTEGRATION—how symmetry-based object extensions are evaluated regarding discernibility within the given object. (Note that Rosch's 'basic level categories' SQUARE, CIRCLE, TRIANGLE, which are assessed to be optimal from the point of view of pattern recognition, are worst from the point of view of dimensional designation due to their lack of axial distinctness.) (iv) SALIENCE/PROMINENCE—how the axes specified so far are ordered within some object x according to their relative extent. This criterion singles out the maximal axis of x, if there is one, and arranges the extensions of x into a proportion schema (hence the name given to this module), (v) PENETRABILITY—whether or not an object, due to certain substance properties (poorly understood as yet), can be visually penetrated or not. Whatever this may be, it is this criterion which makes thickness a spatial property (albeit one where perceptual information is functionally interpreted) and which underlies the complementarity distribution observed with dick (thick) and
E-Lang 135
To show that things like MAX, SUB etc. are not mere labels, but theoretical constructs having a clear-cut interpretation within the scope of the theory, the conditions encoded in e.g. MAX may be spelled out like this: MAX identifies the most extended disintegrated axis of some object x, which in turn presupposes that there is exactly one such axis of x available (remember the inapplicability of lang (long) to circles or squares). SUB identifies either a non-maximal disintegrated third axis (cf. thick board) or an integrated axis forming the diameter of a circular section (cf. thick pole).
Now let us turn to the other device called Primary Perceptual Space (PPS). As one will guess from the name, PPS is meant as a model of space, specifically, as a model of how external physical space is conceptually reconstructed in terms of categorized sensory input delivered by our biological equipment. While IPS is based almost exclusively on vision, PPS has a broader basis in drawing on perceptual input available from the organ of equilibrium, from upright walk, and from eye level, each of which contributes a specific interpretation of external physical space. PPS consists of a set of principles which define three distinct axes which, in turn, define our internal model of the external space at least as far as it concerns dimensional designation of spatial objects. The relevant point is that the three axes of PPS, unlike the ones of a Cartesian system of coordinates, are rather unequal as to their origin and characteristics. It is these axial properties which are decisive for dimensional designation. Whatever the principles may be that are involved in PPS, what they produce are the following three axes: (i) VERTICAL AXIS. Due to its origin in gravitation as perceived by the organ of equilibrium, the vertical axis is constant and ubiquitous; upright walk assigns it a foot and afixed(geofugal) direction. These properties make the vertical superior to the other axes, which in a way are defined in relation to it. (ii) OBSERVER AXIS. Originating in the visual organ, the observer axis has an anatomically determined pivot allowing for a 180 ° turn; the position of the eyes determine its direction (away from the observer) and its orthogonality to the vertical axis. (iii) HORIZONTAL AXIS. This third axis has no endpoints and no direction; it is not
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DIST identifies an object axis perceived as inside diameter of a hollow body. Thus, though SUB and DIST identify the same type of axis in terms of geometry, they draw on mutually exclusive perceptual properties in terms of the theory underlying our everyday knowledge of spatial objects.
136 Primary Perceptual Space and Inherent Proportion Schema
an axis we are equipped to identify by primary perceptual information, but is derived from the two others just to fill the gap determined by the properties of the latter. The PPS thus characterized also functions as a categorization grid which like IPS yields values and parameters for the identification of position properties of spatial objects. Regarding the SF representations of DAs, PPS provides us with the parameters VERT and OBS specifying the dimensional meaning components oihoch: niedrig [high : low, tall) and tief(deep), respectively. If assigned
4 OBJECT SCHEMATA The most plausible way in which conceptual representations of spatial objects may be construed is to render them in the form of a matrix with 3 rows and 1, 2 or 3 columns (depending on the nature and number of the axes of the object represented). We call such a matrix an object schema (OS). An OS contains entries which represent the defining properties of a class of spatial objects. OS are thus representational units of the CS level serving as location frames within which the parameters of the SF level are instantiated. The structure of an object schema and the selection of entries it may contain are again entirely determined by categorizational output of IPS and PPS. Take the head row first. In containing one, two, or three variables for object axes (a, a b, a b c) it represents the dimensionality of the object at issue, the boundedness by angled brackets, the integration of axes by brackets. This yields exactly 7 types of OS as shown in Figure 4. The second row reflects defining gestalt and position properties of the given obj ect, that is entries such as max ,sub, vert, obs etc. Being part of an OS, these symbols now stand for conceptual values instantiating the parameters MAX, SUB, VERT etc. of the SF level (note the typographic distinction). The third row displays the contextual specifications induced by a DA or by the situational context. Finally, by convention the sequence a b c is intended to reflect the order of salience of the axes involved.
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to some spatial object x, VERT identifies exactly that disintegrated axis of x which coincides with the vertical of PPS. OBS identifies any disintegrated axis of x which coincides with the Observer axis of PPS. As noted above, the third axis of PPS does not yield a parameter on its own. This gap is partially filled by a derived parameter ACROSS which accounts for the inherent relativity of breit : schmal (broad, wide : narrow) discussed in (23) above. To conclude this section and link it up with the next one. Figure 3 summarizes the points made so far in an overall diagram.
E.Lang 137
PERCEPTUAL LEVEL Biological Equipment
Object Delimination Symmetry Axes (Dis)Integration of Axes Prominence/Salience Penetrabilty
PRIMARY PERCEPTUAL SPACE
INHERENT PROPORTION SCHEMA
Categorization grids yielding semantic parameters and conceptual instantiations regarding
position properties
gestalt properties
which are merged to OBJECT SCHEMATA CONCEPTUAL LEVEL Figure 3 Justifying/Deriving Conceptual Distinctions in Spatial Objects Physical Preconditions:
Physical Space, Light, Gravitation, Organisms...
To give just one simple example, consider the two OS representing the semantic interpretation of the pole in (3o)(a,b): (30) (a) The pole is 10m long
(a
(b
c))
max sub max
(b) The pole is 10m high
(a
(b
c))
max sub vert
Primary identification is represented by matching entries in the 2nd and 3rd row. Thus max max in (3o)(a) indicates that the DA long identifies the maximal axis of the pole. Contextually induced specification is represented by differing but compatible entries in the 2nd and 3rd row. Thus the combination max vert
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VERTICAL AXIS (constant, ubiquitous, foot, fixed directions) OBSERVER AXIS (pivot, allowing for 180° turn, fixed directions, orthogonal to VERTICAL AXIS) HORIZONTAL AXIS (no end-points, no direction, derived due to orthogonality)
138 Primary Perceptual Space and Inherent Proportion Schema
(31) (a
b
(32) (a) (a
c) I [vert, max, 0 } b
BUILDING
(family concept)
c)
SKY-SCRAPER, HIGH-RISE BUILDING
c)
BLOCK, APARTMENT HOUSE
max0 vert (b) (a
b
max vert 0 (c) (a
b
max 0
c)
HUT or BUNGALOW
vert
(which can be aflat!)
Summing up, I wish to point out some interesting conclusions to be drawn from the analysis in terms of object schemata. First, the inventory of OS shown in Figure 4 reflects essential aspects of OBJECT CLASSIFICATION. Consider the entries in the 2nd row: OS containing dist = hollow bodies (with access opening) sub = solid bodies vert and/or obs = oriented/perspectivized objects neither vert nor obs — freely movable objects etc. Second, the question of what dimensions languages pick out can now be answered more precisely like this: the semantic constants occurring in the SF representation of DAs are just a language-bound subset of the entries occurring in the OS, but both sets are determined as a categorizational output of IPS and PPS. Third, it is now possible to write the 'grammar of admissible object schemata' by formulating a set of conditions on the combinatorial structure of OS (for details see Bierwisch & Lang 1987, 1989; an implementation in Prolog
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in (3o)(b) indicates that the DA high applies to the pole's maximal axis by specifying it as coinciding with the vertical of PPS. (3o)(b) entails that the pole is standing, whereas (3o)(a) is unspecified as to the pole's position. As stated above, the range of admissible entries in an OS reflects exactly the various constraints and compatibility conditions discussed in section 2. Figure 4 presents the inventory of those admissible object schemata for which we were able to find some empirical instance. Figure 4 illustrates that it might also be reasonable to assume OS which are defined only by their head row and the sample of their entries, but which are left open as to the order of salience. Thus (31) gives the BASIC SCHEMA for the family concept BUILDING. It contains the set of flexible entries (vert, max, 0 ) which can be arranged to form the subschemata (32)(a)-(c). This notion of BASIC SCHEMA perhaps lays the ground for further generalizations.
ELang 139
Object Schemata
Spatial Objects
Lang-26
I unbounded
bounded dimensionality
a, b, c
I
No
3 integration of axes No
Yes
BANNER vert DOOR
vert PICTURE
dist HOLE
LINE-SEGMENT
IV
V
VI
sub DISK vert obs PLATE dist sub
III
max YARD max vert
max
Yes
max sub max sub BOARD POLE
dist max vert max PIPE max sub max 4> verl obs vert RIVER TOWER vert <j> sub vert dist WALL BARREL vert obs max dist obs CUPBOARD BOREHOLE vert dist obs TABLE
I VII BALL
RING dist vert POT
obs
WOUND vert obs GRAVE.DEN
ft fe iy '* verl sub BOOK
SPRING Calculation Inventory of dimensionally designatable spatial objects: "" types of OS with about H) possible instantiations
Figure 4 Categorization of spatial objects on the Conceptual Level
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I 2 integration of axes
140 Primary Perceptual Space and Inherent Proportion Schema
such as having a designated side ofaccess or user-oriented side.
The assignment of such properties, which involves the sort of functional factors discussed in Vandeloise (1984; 1986; 1988), can be construed as a projection of function schemata on to object schemata. * This is the revised and extended version of a paper in German that appears in C. Habel, M. Herweg, K. Rehkamper: Raumkonzepte in Verstehensprozessen, Niemeyer, Tubingen. I am grateful to the Journal's anonymous referees for useful critical remarks. EWALD LANG University ofWuppertal FB4, Gauss-Str. 20 D-5600 Wuppertal
REFERENCES Bierwisch, M. (1967), 'Some semantic uniBierwisch, M. (1986), 'On the nature of versals of German adjectivals', Foundations semantic form in natural language', in F. ojLanguage, 3: 1-36. Klix & H. Hagendorf (eds), Human Memory
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was prepared within the LILOG Project, cf. Lang & Carstensen (1990). These conditions may be construed to represent the structure of the module C^« discussed at the beginning. Fourth, once having reached this level of generalization, the theory of object schemata suggests further hypotheses as to the formal as well as substantive properties of conceptual structure. Cf. the stimulating paper by Blutner (in press) who considers object schemata as a means of representing ontological knowledge. Fifth, the object schemata discussed here reflect the basic shape and position properties of spatial objects regarding the dimensional designation of their axial extensions. The information encoded in the object schemata in their present form can easily be extended to cover further spatial features. Thus, in order to identify an object's intrinsic bottom and top or front and back, the axes defined by vert and/or obs in an object schema can be assigned distinct end points, say F, F' and O, O ' respectively. The designation of those end points follows from the inherent properties of the axes involved and is suitable to determine an object's intrinsic bottom and top sides or front and back sides etc. which in turn are crucial to the analysis of local prepositions like above, behind (for details see Lang & Carstensen (1990). Sixth, it seems promising to take the object schemata discussed so far as the basis on which other types of object properties can be represented in a natural way. To mention just two: it is obvious that the characteristics of an object's geometric form (i.e., being circular, oblong, square etc.) do not coincide with, but nevertheless primarily rest on, the object's axial properties as specified in the object schemata. The same applies to functionally defined object properties
E.Lang 141 and Cognitive Capabilities. Mechanisms and
matische und konzeptuelle Aspekte von Dimensionsadjektiven, Akademie-Verlag,
Berlin. Bierwisch, M. & E. Lang (1989), 'Somewhat longer-much deeper-further and further. Epilogue to the Dimensional Adjective Project', in M. Bierwisch & E. Lang (eds), pp. 471-513. Bierwisch, M. & E. Lang (eds) (1989), Dimensional Adjectives: Grammatical Structure and Conceptual Interpretation, Springer-Verlag,
FodorJ. A. (1983), The Modularity of Mind. An Essay of Faculty Psychology, MIT Press, Cambridge, Mass. Harris, P. L, J. E. Morris & M. Meerum Terwogt (1986), 'The early acquisition of spatial adjectives: a cross-linguistic study', Journal of Child Language, 13: 335-52.
Hlebec, B. (198 3), 'A lexico-semantic study of English one-dimension adjectives', Anali filoloskogfakulteta, 15: 243-80, Belgrade. Lafrenz, P. G. (1983), Zu den semantischen Strukturen der Dimensionsadjektive in der deutschen Gegentvartssprache, Goteborg.
Lang, E. (1987), 'Semantik der Dimensionsauszeichnung raumlicher Objekte', in M. Bierwisch & E. Lang (eds), pp. 287-458. Lang, E. (1988), 'Gestalt und Lage raumlicher Objekte: Semantische Struktur und kontextuelle Interpretation von Dimensionsadjektiven', in J. Bayer (ed.), Grammatik und Kognition. Psycholinguistische Unter-
suchungen, pp. 163-91, Westdeut. Verlag, Opladen. Lang, E. (1989), 'The semantics of dimensional designation of spatial objects', in M. Bierwisch & E. Lang (1988) (eds), pp. 263417. Lang, E. & K.-U. Carstensen (1990), 'OSKAR-a Prolog Program for Modelling Dimensional Designation and Positional Variation of Objects in Space', LILOGReport. IBM Scientific Center, Stuttgart. Lehrer, A. (1974), Semantic Fields and Lexical
Berlin, Heidelberg, New York, Tokyo. Structure, North-Holland, Amsterdam. Blutner, R. (in press), 'The ontology of spatial Lyons, J. (1977), Semantics, Vols 1, 2, Camconcepts: the fallacy of the so-called bridge University Press, Cambridge. M-Principle', in Proceedings of the Inter- Vandeloise, Cl. (1984), 'Description of Space national Theodor-Fechner-Symposium, Leip- in French', Dissertation, University of zig. California, San Diego, LAUDT, Duisburg, 1985. Clark, H. H. (1973), Space, time, semantics, and the child', in T. E. Moore (ed.), Cogni- Vandeloise, Cl. (1986), L'espace en francais, tive Development and the Acquisition of Editions du Seuil, Paris. Language, Academic Press, New York, Vandeloise, Cl. (1988), 'Length, width, and pp. 28-63. potential passing', in B. Rudzka-Ostyn (ed.), Topics in Cognitive Linguistics, Clark, H. H. & E. V. Clark (1977), Psychology pp. 403-27, Benjamins, Amsterdam. and Language, An Introduction to Psycholinguistics, Harcourt, Brace Jovanovich, NY.
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Performances, North-Holland, Amsterdam, pp. 765-84. Bierwisch, M. (1987), 'Semantic der Graduierung', in M. Bierwisch & E. Lang (eds), pp. 91-286. Bierwisch, M. (1988a), 'On the grammar of local prepositions', in M. Bierwisch, W. Motsch & I. Zimmermann (eds), Syntax, Semantik und Lexikon, Akademie-Verlag, Berlin, pp. 1-65. Bierwisch, M. (1988b), 'Tools and explanations of comparison', Journal of Semantics, 6: 1.57-93 (Part 1), 6: 2.101-46 (Part 2). Bierwisch, M. (1989), 'The semantics of gradation', in M. Bierwisch & E. Lang (eds), pp. 71-262. Bierwisch, M. & E. Lang (1987), 'Etwas langer-viel tiefer-immer weiter. Epilog . zum Dimensionsadjektiveprojekt', in M. Bierwisch & E. Lang (eds), pp. 649-99. Bierwisch, M. & E. Lang (eds) (1987), Gram-
Journal ofSemantics 7: 143-174
© N.I.S. Foundation (1990)
The Interpretation and Representation of Coreferential Lexical NPs in Expository Texts ALFONSA. MAES Department ofLanguage and Literature, Tilburg University
Abstract
1 INTRODUCTION 1.1 NPrNP'rpairs in expository texts Language users have different means at their disposal to reintroduce an entity in a text. The most obvious possibilities are illustrated in (i) and (2): literal repetition (the NP r NP[-pair) and pronominal reference (the NP r Pro r pair). (1) Yesterday Reagan t (NPj) decided to retire from the White House. Reagan { (NP;) announced his decision during a show on American television. (2) Yesterday Reagan-t(NP,') decided to retire from the White House. He^ (PrOj) announced his decision during a show on American television. Entities can also be reintroduced by an alternative coreferential descriptive NP, i.e. a lexical NP which is different from the antecedent NP (the NP r NP,'pair). NPj-NPj-pairs are illustrated in (3) and (4): (3) Yesterday Reagan; (NPj) decided to retire from the White House. The president { (NP,') announced his decision during a show on American television.
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The central topic of this article is the relationship between coreferential, non-identical, lexical NPs in texts (so-called NPj-NPj'-pairs). The main question in this article is which interpretation and representation must be attributed to the relationship between NPS and NP[ if they are to justify the (referential, cohesive and informative) functions and the adequacy of NP[ in texts. The answer has been given in terms of text relations and text intentions. It has been argued that the adequacy of NPj-NPj'-pairs cannot simply be made dependent upon either the status of the entities involved in the reader's knowledge store, or the surface characteristics of sentences or texts, such as the distance or the structural relation between NP; and NP[. Rather, the adequacy is dependent on the question whether NPrNPj'-pairs are adequate actualizations of implicit text relations which, in turn, have to be adequate specifications of the intentions underlying the text. Such a treatment enables us to construct a representation for NPj-NP;'pairs in which the different functions of NP[s are incorporated.
144 Coreferential Lexical NPs in Expository Texts
(4) Yesterday Reagan; (NP;) decided to retire from the White House. The exmovie star{ (NPj) announced his decision during a show on American television. Alternative lexical coreferential NPs (henceforth called NP,'s) fulfil different discourse functions at the same time:
1.2 Objectives NP r NP [-pairs are the subject of this article. The main question is which interpretation and representation must be attributed to the relation between NP; and NP,' if they are to justify the functions and the adequacy of NP,'s in texts. At the very heart of this article is the notion ofadequate NP't, meaning an NP,' properly fulfilling its three functions in a text. This implies that an NPj' must not just enable the reader to establish the intended reference. We do not take each NP,' enabling the reader to bring about the intended reference to be adequate. There is, for instance, a clear distinction to be made between the NP[s in (5); yet, all these NP,'s are capable of identifying the antecedent NP: (5) In the Senate commission report on the Iran affair, Reagan {was told that hex had left his collaborators too much leeway. [The president i / The head of the White Housei / tNancy's husband; / V.The owner of a ranch in California^ had
omitted to see what was taking place in the cellars of his own official residence. In this text, adequacy is only based on the intuitive evaluation of the coreferential, cohesive and informative functions of the NPj's in a given text environment. The intuitive evaluation can be put to the test because the NP,'examples are provided with the necessary contextual information. No experimental proof is given in this article for the said adequacy. This article deliberately refrains from pursuing the matter of the relationship between NP^ and demonstrative NP'jS such as in (6):
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—firstof all, NP,'s are just like NP; in (1) and Pro in (2) means of identification. Their function consists of identifying a certain entity by establishing a referential link with the antecedent NP; — secondly, NP.'s must be looked upon as means of cohesion in a text: more specifically they find a place among those elements of language which bring about lexical cohesion; — thirdly, NPj's are part of the fulfilment of the intention of a text or a text segment, i.e. not only do they establish a (cohesive and referential) link with the antecedent NP—which is what NPj and Prof do—they also provide information about the entity the NP refers to.1
A. Maes 145
(6) Jan WuytSj is back in the country. This last representative of perspectivistic nihilism in architecture{ has completely lost his charisma.
(7) He loves his wife too much:. He has to go to the psychiatrist with [this /??the problem^. (8) John loves his moped. He's simply crazy about [those vehicles / ??the vehicles}. However, in this article, we will restrict ourselves to the 'pure', nondemonstrative NPj's. This article proposes to deal with the behaviour of the NPrNP,'-pairs in a written expository text. An expository text is to be regarded as a text, the central discourse intention of which is the identification, description and 'exposition' of entities; just as 'convincing' is a central intention of argumentative texts. NP,'s are quite frequent in expository texts. Especially sports reports, travel brochures and non-specialist scientific literature contain a striking number of NP r NP[pairs. The fact that NPrNP,'-pairs principally occur in written language or in 'prepared' spoken language such as, for instance, in the case of newsreaders, is in itself a reason not to look upon NPj-NP^-pairs as a spontaneous means of coreference, but rather as the result of a certain planning in which the different functions of NPrNP,'-pairs must be considered in a concrete text setting. (The use of epithets in conversational context is of course an exception to this planned use of NPrNP,'-pairs.) As such NPj-NP,' in this article is to be looked upon as an 'autonomous identification act on the part of the writer or, in other words, as an act of identification coming about without any form of'collaboration' between the communication partners.2
1.3 Overview In section 2 various characteristics and interpretations of NP-s and NPj-NP,'pairs are commented on and evaluated, the conclusion being that all attempts
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The zealous reader who undertakes to change all the NP[s marked as inadequate in demonstrative NP,'s will find that this change does make a number of NP[s adequate. In some of these cases the adjunction of a demonstrative element to an NP[ makes possible a referential link, at the same time forcing the integration of the lexical load of the NP[ into the text. On the other hand, not all adequate NPj-NPf-pairs remain adequate if a demonstrative is added, as for example in (3). There is empirical evidence for the claim that NPj's and demonstrative NP[s fulfil different discourse functions, as is shown in Maes (in prep.). Among other things, demonstrative NP[s—unlike NPj's—are able to 'pronominalize' entire propositions, as in (7), and to bring about changes in the 'identification mode' of the discourse entity involved, e.g. the change from uniquely identified to generic, as is shown in (8):
146 Coreferential Lexical NPs in Expository Texts
to describe NPrNP,'-pairs from a single function viewpoint are descriptively inadequate because they do not provide us with an integrated picture of all functions of NP-s in texts. In section 3 a proposal is made with regard to the interpretation and representation of NPj-NP'-pairs: the relation between NPj and NP[ is seen as an implicit text relation existing between coreferential discourse entities in the focus space of the discourse representation. 2 DESCRIPTIVE CHARACTERISTICS AND INTERPRETATIONS OF NP;-NP;-PAIRS
2.1.1 Intended coreference When an NP[ in a text is interpreted, it is of the utmost importance that it is interpreted as having the same referential intention as the antecedent NP: both elements aim at identifying the same entity, i.e. they are intended to be coreferential (Evans 1980: 358-60). Moreover, the members of NPj-NPj'-pairs are not interchangeable: they are subject to a relation of dependency. One might think that, given these two characteristics, NPrNP--pairs can be interpreted as NP r Pro r pairs: both characteristics are applicable to NP,' as well as to Pro;. However, such a treatment would lead to insurmountable problems.
2.1.2 NPj"s as pragmatic, referential pronouns In the research on coreference and pronouns, no extensive analysis has been made yet of NP,'. As far as we know, the only nominal anaphors which have been given some sporadic attention are epithets, degree nouns and classifiers (e.g. Bolinger 1977; Bosch 1983; Hinds 1978; Seuren 1985). It is important to note, however, that the attention they have received depends upon their usefulness with respect to the analysis of pronouns. Nominal anaphors, for instance, play a crucial role in Bosch (1983:49) in determining which pronouns occur referentially. Following Bosch, Seuren (1985: 350) also formulates an epithet test for what he calls denoting pronouns.3 The epithet test could be a descriptive reason to regard (at least some) NP,'s as referential pronouns. Such a test is in keeping with the fact that NP,' is ungrammatical in a structural environment where NP[ is syntactically linked with NP;, as it appears from (9) and (10): (9a) John j washes himself\ (9b) *]ohnx washes the hoy^
(10a) Reagan^ says het will continue supporting the contras. (10b) *Reagan, says the president t will continue supporting the contras.4
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2.1 The pronominal interpretation ofNP[
A. Maes 147
And yet, die test is misleading because it is being used as a criterion to distinguish classes of pronouns and, as such, it cannot be indiscriminately used to investigate NP r NP,'-pairs. Even if all (or only) denoting or referential pronouns could be substituted by epithets, this would still not mean that all NP r NP,'-pairs can be replaced by a (denoting or referential) pronoun. Examples such as (1 I ) - ( I 3) appear to confirm this view: NP,'s in those examples cannot be indiscriminately replaced by a (referential) pronoun without producing particularly awkward sentences (the b-versions). All sentences are opening sequences of radio news items:
2.1.3 N P - a n d c - c o m m a n d It follows from these considerations that NP,'s cannot simply be replaced by pronouns. But there is more: NPi's are not bound by the same structural restrictions applicable to referential pronouns, as it appears from the c- and d-versions of (11) and (12): (11c) At the takeover of the Kluwer publishing company it the enterprise, promised no jobs would be lost. (1 id) *At the takeover of the Kluwer publishing company•„it-, promised no jobs would be lost. (12c) In the battle for Assubel,, the insurance company•, has taken an important step in order not to fall into foreign hands. (i2d) *In the battle for Assubel,, it, has taken an important step in order not to fall into foreign hands. When regarded as referential, not bound pronouns, the NP,'s in (1 ic) and (12c) do not obey the restrictions imposed by the so-rcalled primacy relation between antecedent and pronoun/NP,'. The core of this relation is the fact that the pronoun must not c-command its antecedent. Reinhart 1983 formulates this
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(1 ia) At the takeover of the enterprise^ the Kluwerpublishing company {promised no jobs would be lost, (lib) ??At itsi takeover, the Kluwer publishing company i promised no jobs would be lost. (12a) In the battle for the insurance company,, Assubel, has taken an important step in order not to fall into foreign hands. (12b) ??In the battle for if j, Assubel, has taken an important step in order not to fall into foreign hands. (13a) Luc van de Vijver who, for years, was the spokesman of the Compagnie Generate de Belgique it left 'the Grand old Lady ', on 1 st April. (13b) ??Luc van de Vijver who, for years, was the spokesman of the Compagnie Generate de Belgique i? left her, on 1 st April.
148 Coreferential Lexical NPs in Expository Texts
restriction as follows: 'A given NP must be interpreted as non-coreferential with any distinct non-pronoun in its c-command-domain' (Reinhart 1983:43). According to this rule, the Kluwerpublishing company in (1 ic) and (1 id) cannot be coreferential with the enterprise I it, because it is a distinct non-pronoun with the c-command domain of the NP the enterprise I it. This rule appears to be applicable to (1 id) and (i2d) but not to (1 ic) and (12c). A striking fact is that the 'illegal' c-variants of (11) and (12) are by far more acceptable than the legal a-vanants.5
2.1.4 The precede-relation between NP{ and NP,'
(14) [advertisement] Tomorrow, the master of the French chanson; will appear in the Arenburg theatre. This will be Gilbert Becaud's twelfth Belgian appearance. Cases such as these can be compared with backward anaphors. They draw their effect and their function from the violation of the precede-condition (see Maes 1987). 2.1.5 'Antecedentless' NP,' Although we are concerned here with 'full' NPrNP,'-pairs, there are lexical NPs which can be looked upon as being 'antecedentless' NP,'s. Metaphorical lexical NPs such as in (15) and (16) can serve as examples: (15) [advertisement, picture of the Lada Samara 1300 J The most sold 13001 widens its scope.
(16) [theatre review, newspaper L. Vandervostx plays the part of Hamlet in an adaptation by theatrical company 'De Tijd'] Hamlet {was tired after the performance in Volendam. In these cases, it can be argued that NP; (Lada Samara 1300 or L. Vandervost) can be inferred on the basis of available information (in the context, situation or knowledge base). This means that in the mental representation an entity must be present which can be said to be dominant for the entity of which NP[ is the actualization. On account of their lexical nature, such 'defective' NP r NP,'pairs—as we may call them—are more powerful than defective PrOjS when it comes to bringing about a certain reference. They can appeal to lexical
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What does remain of the similarity between NP,' and Pro; is the fact that NP,'s, like referential pronouns, have a relation of 'intended coreference' with the antecedent NP. In order to be recognized as being coreferential, it goes without saying that NP; must precede NPj'. However, this weak precede-condition can be violated, as in the case of the intended coreferential pronouns:
A. Maes 149
knowledge and world knowledge shared by the communication partners and must not only be based upon contextual or situational knowledge, as is the case with defective Pro;s. On the other hand—unlike defective PrOjS—they are subjected to the pragmatic restrictions we will outline further for NP r NP,'pairs.
2.2 The topical interpretation ofNP]
(17) Who did you calm when you saw him getting mad? ??I calmed the idiot;, before Harry { did something rash. The NP,' can also function as a selection mechanism, namely when different topic candidates present themselves in the preceding context, as in (18): (18) . . . Recently she has switched Brussels { for Tilburgy And yet, she regularly goes back to her place of birth yy
If one accepts that the topical value of NP,' is sufficiently indicated by the conclusion or the condition that NP,' must refer to the topic of the text, the following problems remain unsolved: — The condition is applicable to Pro; and to NP;', thus leaving the Pro;-NP,'differences in the examples ( I I ) - ( I 3) unresolved. These differences can only be explained if one accepts that the topical value of NP^is different from the topical value of Pro; (see 3.3.3). — Not all NPrNP,'-pairs referring to the topic of the text are adequate. In other words, the topic condition for NP[ is indeed a necessary condition, but not a sufficient one. See (19): (19) On 18th March 1612, for the first time a human 4 set foot on the island of Ebreo. (He; started to build a hut right away. / P.The woman{lived there for twenty years.) When NP,'firstappears in (19) there is obviously only one topic candidate. And yet, the NP,' is not adequate. This is the consequence of the fact that the given
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Like Proi; NP,' is not only a means of reference to an antecedent NP, but also an indicator of what a sentence or text is about. The literature on pronouns adopts different views on and proposals for this topical function. Bosch (1983: 205) for one formulates the 'aboutness-principle', to which both Pro; and NP-anaphors are subject, as follows: 'An anaphorically used expression refers to an object which the discourse at the relevant moment is about.' So, like a PrOj, an NP,' is the reintroduction of topical text elements.6 Proof of this can be found in the fact that NP[ is inadequate at the time NP; has not yet been activated, as in (17), a variation on an example of Kuno (1975: 283):
150 Coreferential Lexical NPs in Expository Texts
topical description of NP,', like the referential interpretation of NP,', does not enable us to impose restrictions on the informative load of NP[ (see 3.3.2.2 and 3.3.3).
2.3 The interpretation ofNP\ in terms oflexical cohesion and shared knowledge 2.3.1 NP,'as cohesive elements
Reiteration is a form of lexical cohesion which involves the repetition of a lexical item at one end of a scale; the use of a general word to refer back to a lexical item, at the other end of the scale; and a number of things in between—the use of a synonym, near-synonym, or superordinate. (Halliday & Hasan 1976: 278)
According to Halliday & Hasan (1976: 284), the cohesive value of these lexical items must be distinguished from the referential function: Properly speaking, reference is irrelevant to lexical cohesion. It is not by virtue of any referential relation that there is a cohesive force set up between two occurrences of a lexical time; rather the cohesion exists as a direct relation between the forms themselves (and thus is more like substitution than reference).
This may follow from the fact that alternative NP;s, and certainly literal repetitions, create a cohesive link without being coreferential, such as in (20): (20) My car proved to be worth nothing. Any new car will have to be a lot more reliable. The distinction between referential and cohesive functions has been carried through by Stotsky (1983: 441). In her dichotomy—which is based upon the Halliday & Hasan dichotomy—coreferential and non-coreferential cohesive elements mingle: — semantically interrelated words (elements systematically related to a preceding element via, for instance, repetition, synonymy, opposition, inclusion, and so on); — collocationally related words (elements related to other elements via frequent co-occurrence in similar contexts). Experimental research as conducted by Garrod & Sanford 1977 provides further evidence for a distinction between the referential and the cohesive function of NP,'s. They proved there was no difference in processing time between sentences like (21) and (22):
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An NPj' is a lexically cohesive element. In the dichotomy of lexical cohesion as proposed by Halliday & Hasan (1976: 274-92) the NP,'s—together with the literal repeated NPs—constitute the cohesive elements of'reiteration':
A. Maes 151
(21) A bust came trundling down the hill. A pedestrian was killed by the vehicle,. (22) A bus came trundling down the hill. It nearly smashed into a vehicle. The lack of difference in processing time between (21) and (22) is attributed by Sanford & Garrod 1981 to the fact that readers conduct a similar semantic check on the sentences (21) and (22). Such a semantic check is obvious in (21) because it is essential to the correct interpretation of the referential identity between 'bus' and 'vehicle'. The fact that the processing time of (22) is the same as that for (21) proves, according to Sanford & Garrod, that a similar check takes place when (22) is processed. In other words, readers still construct a link between the semantically related elements 'bus' and 'vehicle' although they are not coreferential in the text.
If NP,'s are ordinary cohesive elements, the question is why readers regard them as cohesive elements. An obvious answer to that question would be that NP[ is regarded as cohesive with NP; on the basis of 'shared knowledge' or 'familiarity'.7 On the basis of this statement, the adequacy of an NP,' can be made dependent upon the condition that it contains information which is 'familiar'.8 This condition seems justifiable in the light of inadequate NP r NP,'pairs such as the one in (23): (23) [starting point: few know that Anatoli Karpov is a keen stamp collector] ??AnatoliKarpov{ has been operated. The stamp collector^ medical condition is satisfactory after one day. This 'familiarity condition' is in keeping with the classes distinguished by Stotsky 1983. She distinguishes two types of cohesive elements on the basis of two types of knowledge possessed by the reader free from any concrete text setting: first, the knowledge of the intrinsic semantic similarity between lexical elements; and secondly, the knowledge of the frequent co-occurrence of lexical elements in similar contexts. Experimental evidence for such a familiarity condition can be found in Sanford & Garrod 1981. They refer to research (Sanford & Garrod 1973) proving that the verification time of NPrNP[-pairs, especially in the case of classifiers, is dependent upon the semantic relation existing between NP; and NPj'. The processing time diminishes as the degree of 'conjoint frequency' increases. This frequency is to be looked upon as a 'joint function of the category and the exemplar' (1981: 108). A simplified version of these findings would be: the more familiar, the quicker.
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2.3.2 The familiarity condition on cohesive NPj's
152 Coreferential Lexical NPs in Expository Texts
2.3.3 Objections to the familiarity condition An adequacy condition on NPrNP,'-pairs in terms of 'familiarity', 'shared knowledge' or 'conjoint frequency' between NP,' and NP; seems obvious both from an intuitive and from a psychological viewpoint Still, the condition is contestable from both a descriptive and a theoretical viewpoint
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a. In a discourse representation a familiarity condition can hardly be formalized. Whatever can be introduced in a text as 'familiar' or 'new' with regard to a certain entity will depend upon the question what can be regarded as being part of the presumed knowledge-store of the reader. There is a high degree of redundancy in what should be formalized in the representation as familiar information about text entities: far more is familiar than what is actually used in a concrete text setting. In addition, the dividing line between what is familiar and what is new will be different from reader to reader.9 b. The experimental finding (Sanford & Garrod 1981) of a relation between processing ease and familiarity (conjoint frequency) is, with regard to our adequacy analysis, incomplete and misleading. It is misleading because it is inadmissible to interpret differences in processing and/or verification time between different NPrNPj'-pairs simply in terms of NPj'-adequacy: the fact that high conjoint frequency NPrNP,'-pairs are easier to process only indicates that in die language user's practice diey probably occur more often than low conjoint frequency NPi-NPj'-pairs but it does not necessarily shed light on their adequacy. It is incomplete because the adequacy of NP r NP,'pairs is not only determined by (text independent) semantic relations between the elements of the NPj-NPppairs, but also by text-dependent intentions, as appears from c, d, e, f below.10 c. NPj-NPppairs which are not 'familiar', 'conjoint frequent', or which have no fixed semantic and/or lexical link, can still be adequate in a specific text environment. See for instance (24):
(24) The first novel of the unknown director Frank Vriesakker{, deals with the themes of guilt and responsibility. In his films the son of a calvinist preachert has already shown a predilection for those themes. The examples (25) and (26) are similar: if we assume diat bodi Schmidt's characteristics of an 'ex-Nazi' and a 'drug dealer' are equally novel, the familiarity condition does not explain why the following texts are both adequate and functionally different: (25) [newspaper item; J. Schmidt is unknown] The Hamburg police arrested Josef Schmidt ; yesterday. The ex-Nazi t appeared to be a drug dealer.
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(7 j [newspaper item; J. Schmidt is unknown] The Hamburg police arrested Josef Schmidt i yesterday. The drug dealer { appeared to have been a Nazi. The familiarity condition does not explain why (27) and (28) are both inadequate: (27) ??The Hamburg police arrested Josef Schmidt; yesterday. The drug dealer; appeared to be a dealer in drugs. (28) ?iThe Hamburg police arrested Josef Schmidt t yesterday. The ex-Nazi, appeared to have been a Nazi.
(29 ) [At a press conference Reagan introduces his new press chief Donald Baker who, as is well known, happens to be the grandson of Jesse James. The fact that he was going to be the new press chief, however, had been known for some days throughout the whole world and was certainly known to the press people. The press conference is to be looked upon as a kind of'inauguration' of the new press chief] (29a) This is Donald Baker;. Hex is the new press chief. From now on he will speak to you every Wednesday afternoon. The new press chief{... (29b) ?This is Donald Baker {. From now on the new press chief • will speak to you every Wednesday afternoon. (29c) ??This is Donald Baker j. The grandson of Jesse James, is the new press chief... The NPj's under (29b) and (29c) are inadequate although the relation between NP[ and NPj is knowledge shared by speaker and listener. e. A familiarity condition does not explain why NPs which, with regard to the reader's knowledge-store cannot be regarded as equally available, familiar or well known, can, in a concrete text setting, still occur in both sequences and dependency relations. Compare (30) and (31), both providing us with adequate discourses: (30) The aquila heliaca is a bird of prey. It lives by hunt and fishing. It has a wing span of 1 meter. It is also called the imperial eagle. (31) The imperial eagle is a bird of prey. It lives by hunt and fishing. It has a wing span of 1 meter. It is" also called the aquila heliaca.
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d. NP r NP,'-pairs which are familiar, conjoint frequent or have a fixed semantic lexical relation, do not have to be adequate in just any text environment. Compare for instance (29a), (29b) and (29c):
154 Coreferenrial Lexical NPs in Expository Texts
£ Conversely, the familiarity condition does not explain why NPs which, with regard to the reader's knowledge-store are equally 'available' or, in other words, equally 'familiar' or 'novel', can be subject to a preferential sequence in a concrete text setting. The sequence of the familiar preferential NPs in (32a) will have to be preferred to the inverse sequence shown in (32b):
2.4 Conclusion Three conclusions can be drawn from the foregoing: — The referential behaviour of NPrNP[-pairs is not quite the same as that of referential pronouns. — The fact that only topical elements can be reidentified in an alternative NP, does not tell us anything either about the adequacy of NP,'s or about the differences in acceptability between NP,'-Prorpairs and NPrNP,'-pairs. — The informative load or cohesive value of NPj-NPj'-pairs cannot be interpreted off-hand as 'shared knowledge' or 'familiar' information.
3 NPi-NP.'-PAIRS, T E X T I N T E N T I O N S AND IMPLICIT TEXT RELATIONS 3.1 Introduction From the above it appears that referential or cohesive NPpNPpproposals do not provide us with a satisfactory treatment, especially with regard to the informative function of NPrNP,'-pairs. Furthermore, from the examples in section 2.3.3 it appears that the adequacy of the NPrNP,'-pairs is dependent on the underlying text intention rather than on the opposition familiar vs new. In other words, the function of the NPrNP,'-pairs is to be found in the role they play in the specification of the text intentions. The following section aims at formalizing such an interpretation (section 3.2) and at indicating (in section 3.3) how the interpretation manages to integrate the various functions of the N P r NPj'-pairs, thus eliminating the objections quoted in section 2.
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(32a) [official press release] On the occasion of the formation of his tenth cabinet in a row, W. Martens-twill be received with pomp and circumstance in the royal palace. There, the prime ministeri will receive a golden cup. (32b) [official press release] On the occasion of the formation of his tenth subsequent cabinet, the prime minister, will be received with pomp and circumstance in the royal palace. There, W. Martens; will receive a golden cup.
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3.2 NPrNP'rpairs
and implicit text relations
3.2.1 Intention-based discourse representation
Since the CPs (conversational participants) can never know the whole set of intentions that might serve as DP/DSPs, what they must recognize is the relevant structural relationships among intentions. Although there is an infinite number of intentions, there are only a small number of relations relevant to discourse structure that can hold between them. (Grosz & Sidner 1986: 179)
Although this 'minimal' apparatus may well be sufficient for recognizing relevant relations between intentions underlying discourse, it is clearly not sufficient for recognizing—let alone fully determining or characterizing— subtle interpretation aspects in discourse, such as those demonstrated in N P r NP,'-pairs. Nor is it meant to. Even a list of possible intentions isn't enough to recognize the informative value of NPrNP[-pairs. At best, intentions or basic structural relations between them make possible a rough classification of utterances in a discourse. But they are unable fully to characterize (relations between) these pieces semantically, or to evaluate the contribution of these pieces in the recognition process of text intentions. One way of 'enriching' the recognition process is the postulation of an intermediate level of representation between intentions and utterances. Such an intermediate level should be able to map utterances on to intentions and to evaluate or characterize the contribution of discourse utterances in the intention recognition process. A psychologically plausible formalization of such an intermediate level isn't readily available. For the phenomena under scrutiny here, however, we can confine ourselves to postulating such an intermediate level, i.e. the level of the determination or specification of text intentions. In order to achieve dus, we indicate which text relations or coherence relations hold between the propositions underlying the utterances of each text segment. Such relations are comparable to the rhetorical structure (RS) schemes in the RS-theory of Thompson & Mann 1987.11 In our view, they
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Especially in computational linguistics research, proposals have recently been made to generate and/or represent a text as a whole of hierarchically ordered text (segment) intentions. Grosz & Sidner 1986, for instance, take a text to be a whole of hierarchically constructed discourse segments—each an aggregation of discourse utterances—with at the basis a 'discourse segment purpose'. Grosz & Sidner take discourse (segment) purposes (DP/DSPs) to be intentions meant to be recognized by the reader. They distinguish different types of intentions that could serve as DP/DSPs and two structural relations between them: the relation of dominance and the relation of satisfaction-precedence. These structural relations between intentions are regarded as basic ingredients in the recognition process:
156 Coreferential Lexical NPs in Expository Texts
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are labels covering the propositions underlying the utterances of a discourse and the inferences to be drawn by the reader if he wants to be able to assign an interpretation to the utterances, an interpretation which is similar to the interpretation of the coherence relations of Hobbs 1985. Text relations representing the specification of text intentions are empirically and theoretically highly problematic. First, the relation between utterances and intentions is not predictable: the same text intention can be realized in different ways, i.e. by means of totally different constellations of text relations. Second, as there is no definitive list of all possible intentions underlying discourse (Grosz & Sidner 1986:179), there is no definitive list of all possible text relations underlying discourse either. Moreover there is no consensus about the question whether such a list has to be open-ended or finite. Third—and more important—there is the problem of the plausibility of postulating text relations as devices at work during the processing of language. It has not been proved that text relations represent information which readers need during processing. Grosz & Sidner (1986:202) even claim that 'a discourse can be understood at a basic level if the OCP (other conversational participant) never does or can construct, let alone name, such rhetorical relationships'. However, we suggest that text relations operate at a level linking utterances to intentions. One reason for doing so is that we are concerned here with phenomena exceeding 'basic level understanding', i.e. phenomena which can never be accounted for if only Grosz & Sidner's minimal recognition ingredients are postulated. The second reason is that we do not care how exactly the recognition process (of NPrNP,'-pairs) in individual cases takes place; instead, we are concerned with the different interpretation aspects of NPj-NP,'pairs in formal discourse. This requires an analytical position yielding an idealized, normative representation of discourse, containing not just what is necessary for 'basic level understanding'. In such a representation text relations are an adequate way of expressing the possible inferences and semantic relations underlying discourse utterances. In this perspective, they are meant as analytical tools, as descriptive categories, characterizing the relation between the propositions underlying the utterances. Not the processing value of text relations, or their predictive value in the recognition process, is under discussion here, but their analytical and explanatory value. To avoid terminological confusion, we will refer to the link between intentions and text relations by the terms 'specify' and 'specification'; the link between text relations and actual utterances will be referred to by the terms 'actualize' and 'actualization'. Apart from a component where the specification of discourse (segment) purposes is represented in the form of text relations (TR-component), a component is necessary to verify which entities, which characteristics of these entities and which relations between those entities are active at which precise
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moment of the discourse. Grosz & Sidner 1986 call this component the 'attentional state', which is, in other words, the formalization of the focus of attention in a text. In the representation this attentional state takes shape via (a succession of) 'focus spaces' in a FS-component. Although not everything has yet been said concerning such an intentionbased discourse representation, the above will suffice as a framework allowing us to indicate how NPj-NP-pairs must be interpreted and represented. Within this framework a simple text such as (29a) might be represented as in (3 3): (29a) a This is Donald Baker{ b He; is the new press chief. c From now on he {will speak to you every Wednesday afternoon. D. BAKER as NEW PRESS CHIEF
TEXT RELATIONS (TR):
FOCUS SPACE (FS):
a define D. BAKER b define D.B. as NEW PRESS CHIEF c elaboration D. BAKER/PRESS CHIEF
D. BAKER, PRESS CHIEF
3.2.2 NP ; and NP- as separate, dependent, identically indexed discourse entities in the focus space Grosz & Sidner's attentional state is to be regarded as a dynamic discourse component, a focus mechanism 'measuring' the availability of entities during discourse.12 Given such a discourse component, NP r Pro r pairs can be understood to be referring to a single discourse entity: the focusing mechanism determines the availability of the entity at each moment of die discourse. On these grounds it is possible to decide whether a discourse entity can be instantiated as a pronominal form. Morphological and syntactical rules will then guarantee a correct choice of the pronominal form. These pronominal forms must only be used under certain conditions, i.e. when the entity they are referring to is in focus. This mode of production and representation is not applicable to coreferential NPs. On the grounds of the variables allowing a focusing mechanism to determine the availability of an entity at any given moment of the discourse, it is possible, however, to determine whether the NP; the NP,' refers to is in focus, but it will be utterly impossible to ascertain at which moment of the discourse which NP[ is an adequate lexical alternative for the NPj. Moreover it is impossible to determine which entities can be preferential merely on the basis of a text-independent knowledge representation. However well-known the relation between the concepts REAGAN and MOVIE STAR may be (in other words, they are related to each other in a certain way in any
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(33) TEXT INTENTION: define/present
158 Coreferential Lexical NPs in Expository Texts
conceivable knowledge representation), this does not necessarily mean that, as an NPrNP,'-pair, they are adequate in any conceivable text. It follows that the unpredictability and text dependency of NP[ requires the elements of NP r NP,'pairs to be represented as separate discourse entities in the focus space. The fact that we are dealing with separate entities does not mean, of course, that they can be represented independently of each other in the focus space. The entity NP,' refers to is referentially dependent on the NPrentity. This dependency is expressed in the representation by an identical index of the coreferential entities and by indicating the direction of the dependency (a— b meaning a is dependent upon b).
This index, however, merely represents the coreferential relation between NP; and NP,'. Nothing has yet been said about the informative value of NP,'. It can be formalized in the representation by accepting an implicit text relation between coreferential discourse entities in the FS—as opposed to the 'explicit' text relations represented in the TR-component (i.e. text relations which hold between the explicitly realized propositions of the discourse). The focus space of (3) and (32a) for instance, includes the following representation:13 (3a) REAGAN;
*—PRESIDENT; (identity) (32a) W. MARTENS; « PRIME MINISTER; (identity)
The idea to represent the relation between the elements of NPrNP,'-pairs as implicit text relations can be compared with some of the proposals made regarding definite descriptions. Kleiber 1984 analyses the semantic content of French constructions of the type 'ce + Noun' as 'ce + est + N'. Ortony 1978 takes the viewpoint that definite descriptions are based upon predicates which can either be derived from the preceding context or which are based upon shared knowledge. And,finally,a similar proposal to look upon relative clauses as underlying all NPs has been made by Bach 1968. Next we will indicate how implicit relations can integrate the different functions of NPj-NPj'-pairs in texts.
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3.2.3 Implicit text relations between NP; and NP;'
3.3 The integration ofthe different/unctions ofNPrNP'rpairs 3.3.1 The referential dependency of NP;' A text relation can be conceived of as a characterization of the rhetorical interaction between a satellite and a nucleus (Thompson & Mann 1987: 89). This
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implies that each text relation has to link two or more elements. These elements can be entities, clauses, sentences or parts of texts. This also implies that there is a certain dependency relation between these elements. The right entity owes its existence only to its relationship with the dominant left entity. The left-right sequence in the representation of implicit text relations mirrors the linear sequence of NPrNP,'-pairs in a text: as a rule the dominant NP; precedes the dependent NP[ (see the exception in section 2.14, however). As such, text relations are capable of representing the dependency within NPrNP[-pairs.
3.3.2 The informative value of NP; By representing the NPrNP,'-pairs as implicit text relations the informative value of NP,' is characterized as the value the NP,' has in the whole of the text relations and text intentions. In this respect 'informative' does not refer to the fact diat NP[ adds information to the knowledge-store of the reader but rather to the fact that NP,' adds a relation to the whole of text relations of the ongoing text. Numerous text relations are of the identifying type, i.e. 'equals' (definition, reformulation), 'is an element of the class of1 (classify) or 'has the attribute' (attribute) (see e.g. (3) and (32)). But NPrNPj'-pairs are not at all limited to this, as is shown by the following examples. The a-versions of the examples give a representation of the NPrNP,'-pairs in terms of implicit text relations; the b-versions give an explicitation of the propositions mat can be taken to be at the basis of the implicit relations. The fact that these implicit propositions are indeed the consequence of the NP;-NP,'-pairs becomes clear when one replaces NP,' by PrOj: the given interpretations in the b-versions become invalid. (4)
Yesterday Reagan i decided to retire from the White House. The ex-movie stari announced his decision during a show on American television. (4a) REAGAN; EX-MOVIE STAR; a. (identity) b. (sequence) c. (evaluation) d. (circumstance) (4b) a. 'Reagan is the ex-movie star in question.' (identity) b. 'Reagan used to be a movie star.' (sequence) c. 'Reagan—according to the author—is a movie star (and that is all he has ever been)' (evaluation) d. 'Circumstances are such that Reagan, being an ex-movie star, announced his retirement in a show on television.' (circumstance) (24)
The first novel of the unknown director Frank Vriesakker, deals with the
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3.3.2.1 Informative value and implicit text relations
i6o Coreferential Lexical NPs in Expository Texts
(24a)
(24b)
(34)
(34b)
(35)
former left back ofBeerschot { scored two goals.
(35a) PATRICK VERVOORT;*- - -FORMER LEFT BACK OF BEERSCHOTj a. (identify) b. (sequence) c. (circumstance) (35b) a. 'Patrick Vervoort is the (former) left back (of Beerschot) in question.' (identity) b. 'Patrick Vervoort used to be left back with Beerschot.' (sequence) c. 'Circumstances are such that P.V. as a former left back of Beerschot, scores two goals against his former team.' (circumstance) (36) At the Berlin film festival, the latest film by John Willey { was awarded a prize. The busy director\ could not attend the prize award ceremony. (35 a) JOHN WILLEY^ - -THE BUSY DIRECTORi a. (identity) b. (attribute) c. (reason). (36b) a. 'John Willey is the director in question.' (identity) b. 'John Willey is busy.' (attribute) c. 'Because J.W. is busy, he cannot attend the prize award ceremony.' (reason)
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(34a)
themes of guilt and responsibility. In his earlier films the son ofa calvinist preacherx has already shown a predilection for those themes. THE UNKNOWN DIRECTOR-*—THE SON OF A FRANK VRIESAKKERi PROTESTANT PREACHER; a. (identify) b. (justification) a. 'FV is the son of a protestant preacher.'(identify) b. 'FV deals with the themes of guilt and responsibility, since FV is the son of a calvinist preacher.' (justification) It is said that Ronald Reagan {is not in control of his own domestic staff. Often the most powerful man in the worlds is being shamelessly laughed at by his maids. REAGAN^—THE MOST POWERFUL MAN IN THE WORLD; a. (define) b. (concession) a. 'Reagan can be called the most powerful man in the world.' (define) b. 'Although Reagan is the most powerful man in the world, he is still being bossed about in his own house.' (concession) In the match against Beerschot, Patrick Vervoort { was the best player. The
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3.3.2.2 Pragmatic conditions on NPj-NPj'-pairs Implicit text relations like the ones in the a-versions in the above examples or implicit propositions as in the b-versions are characterized as follows. Obvious is first of all the fact that not all implicit text relations are applicable to all N P r NP[-pairs. Secondly, postulating implicit text relations or inferring implicit propositions is not a necessary condition for a coherent interpretation of a text, which is in contradiction with explicit text relations, whose acceptance is a necessary condition for any coherent interpretation of a text. On the grounds of these characteristics, two pragmatic conditions can be formulated applicable to implicit text relations, i.e. the condition of relevance and the condition of centrality. Those conditions are to be regarded as conditions of adequacy for the informative load of NP-. They are capable of explaining the inadequacy of the problematic NPrNP,'-pairs under 2.3. Condition of relevance as applied to implicit text relations between coreferential discourse entities: An implicit text relation has to relate in a relevant way to the intention of the text (segment) concerned. On the basis of this condition, an NPrNP,'-pair will only be adequate if based upon an implicit text relation which is relevant to the text intention. In other words, a reader must be able to found an NPrNP,'-pair on an implicit text relation or proposition which, drawing upon his knowledge of the kind of text, the text objective and the preceding context he conceives to be a relevant addition to the ongoing discourse. This does not explain how the notion of relevance is to be exactly conceived of or how it is to be formalized; it is only claimed that such a notion is more helpful in determining the adequacy of NP— NPj'-pairs than the notions of shared knowledge or familiarity. And that is what this article has set out to do.
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This kind of analysis is in principle applicable to defective NPrNP;'-pairs as well. The NP,' in (15) 'the most sold 1300', for example, can be interpreted by establishing an 'attribute/evaluation'-relation between two preferential discourse entities (LADA SAMARA 1300-0—MOST SOLD 1300;). A detailed description of this sort of'defective NPj-NPj' pair' (especially of the actor-roletype) can be found in Fauconnier (1985). He is particularly interested in the formalization of the 'mental distance' which, in different text environments, can exist between trigger (that which is written, namely the most sold 1300) and target (that which is meant, namely Lada Samara 1300). He considers the relation as a pragmatic function. However, it does not appear from his analysis which is the function of such mental leaps in a concrete text, in other words, which may be the different values of the pragmatic function. In our approach, this value can be expressed by means of text intentions and text relations.
162 (Preferential Lexical NPs in Expository Texts
Examples such as (23) and (29c) infringe upon this condition of relevance. (23) V.Anatoli Karpov{ has been operated. The stamp collector^ medical
condition is satisfying after one day. (29c) ??This is Donald Baker{. The grandson of JesseJames {is the new press chief
NPj 'Karpov' and NP,' 'stamp collector' resp. 'D. Baker' and 'Grandson ofJesse James' cannot possibly be reduced to any implicit text relation relevant to the intention of the text. The cases (37) and (38) are slightly different. The implicit text relations expressed by the NPrNPi'-pairs are relevant to the text intention in their own right but they are not yet relevant at that particular moment in the discourse:
On the grounds of such examples, relevance has to be understood as 'relevance with regard to the text moment concerned', in other words with regard to the text segment intention applicable at that particular moment and to the corresponding explicit text relations as specified up to that moment. This conception of relevance has the major advantage of offering a set of possible text relations as a testing criterion, which contrasts to the relevance condition proposed by Ortony 1978 for definite descriptions in texts: The predicate underlying a definite description of inference is constrained by the relevance relation injust the same way as the relation constrains what counts as an indirect speech act in a discourse. For an indirect speech act to be understood as being relevant, or appropriate, it must be able to participate as a premise, or as a subconclusion in a quasi-logical, or better psychological chain of reasoning that plausibly relates the event that initiates it to its intended illocutionary force. (Ortony 1978: 76)
Evidence for such a relevance condition can be found in Ortony & Anderson 1977. By way of experiment, they put the difference between 'names' (values) and 'definite descriptions' (roles) to a test. They accept that both names and definite descriptions can be used both referentially and attributively. The referential use of names (39a) and the attributive use of definite descriptions (39b) they call 'direct'; the attributive use of names (39c) and the referential use of definite descriptions (39d) they call 'indirect'. (39a) Alfred Nobel wore a fine beard. (39b) The inventor of dynamite had a profound influence on the nature of warfare. (39c) Alfred Nobel had a profound influence on the nature of warfare. (39d) The inventor of dynamite wore a fine beard.
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(37) V.A woman {was walking in the street. The mortal remainsi were shot down. They; were quickly removed. (38) ??Mr. Klaassen; came home yesterday. The victim; found out all his money had been stolen. He{ hid his money in his pillow.
A. Maes 163
A recognition-test allows Ortony & Anderson to find evidence for the fact that while processing, test persons replace indirectly used names and definite descriptions by their direct variants. This is shown by the fact that cases such as (39c) and (39d) are less well memorized. Two aspects of diis experiment are relevant as far as the NPrNP,'-pairs analysis is concerned:
(40a) Alfred Nobel i was born just before the First World War. The inventor of dynamite { had a profound influence on the nature of warfare. (40b) The inventor of dynamitei had a profound influence on the nature of warfare. Alfred
Nobel{...
— NPs (names or definite descriptions) are characterized as being (in)direct on the grounds of their (ir)relevance in the text environment. (In)directness can consequently be regarded as (inadequacy. The fact that indirect NPs are harder to memorize than direct ones indirectly indicates that language users have an eye for the adequacy of NPs in a sentence. These findings make it possible to arrive at a condition of relevance for the adequacy of NPrNP,'-pairs along the lines suggested above. However, this does not mean that any NP'relevant in a certain text environment also produces an adequate NPj-NPppair. This appears, for instance, from an example such as (29b). For those cases another pragmatic condition applicable to implicit text relations seems to be involved. Condition of centrality as applied to implicit text relations between coreferential entities: Implicit text relations must not be the specification of central text (segment) intentions. With respect to NPrNPi'-pairs this means that they cannot be the actualization of text relations which are part of the specification of the central text (segment) intention. Put differently: propositions underlying M^-N^'-pairs must not be
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— The examples used in the experiment clearly show that the 'direct-ness' of NPs in a text is not the same as referential force (regarded e.g. as a referential hierarchy going from proper names to non-referring expressions). In a concrete text setting, a 'role'-term (39b) can indeed be more 'direct' than a 'value'-term (39c), although the latter has an intrinsically higher referential force. With regard to our NPj-NPppairs analysis, this means that pairs of the type 'NPj — value & NP[ — role' (40a) as well as of the type 'NP[ — role & NP; — value' (40b) can be adequate in texts or, in other words, that both value entities and role entities can be dominant in a NPpNP
164 Coreferenrial Lexical NPs in Expository Texts
necessary in order to achieve a coherent interpretation of a text segment. The violation of this condition of centrality explains the awkwardness of (41): (41) IThe president ofCosta Rica {has postponed the elections in his country. The suffering president; has been flown to the United States.
(30a) ??77ie aquila heliaca {is a bird of prey. The imperial eagle, hves on hunt and fishing. The entity IMPERIAL EAGLE in the representation of (30) is part of an explicit 'define'-relation in which the entity AQUILA HELIACA is defined. This relation is at the core of the fulfilment of the text intention 'define AQUILA HELIACA'. Only after the establishment of this relation, 'imperial eagle' and
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The only thing one can go on when trying to arrive at a coherent interpretation of the two sentences is the attribution of a 'reason'-relation underlying the N P r NP,'-pair in question. It follows that this relation must not be actualized in an implicit form. Elements in favour of the acceptance of the condition of centrality can further be found in the sentences (2oa)-(29b), (27)-(28), (3oa}-(3i). On the grounds of the text intention (REAGAN introduces D. BAKER as the NEW PRESS CHIEF), the 'define'-relation between D. BAKER and NEW PRESS CHIEF in (3 3) is a necessary part of the explicit text relation structure: the 'define'-relation is a necessary part of the specification of the central text intention. In (29a) this explicit relation has been adequately actualized. In (29b) this is not the case: the central text intention has been specified in an implicit text relation between the discourse entities D. BAKER and NEW PRESS CHIEF (and further actualized in the NPrNP[-pair 'D. Baker'; and 'new press chief'i) which, at that particular moment, are not yet coreferential entities in the focus space. Only after and as a consequence of the explicit 'define'-relation (b) will they be available as coreferential entities. A similar explanation can be proposed for the inadequate NPrNP[-pairs (27) and (28): the inadequacy can be reduced to the same breakdown between actualization and representation: the NPrNPi'-pairs provide an inadequate actualization of what, on the grounds of text intention and TR-component, has to be expressed explicitly, namely the 'reason'-relation between, in (27), JOSEF SCHMIDT, WAS ARRESTED, DRUG DEALER, and, in (28), between JOSEF SCHMIDT, WAS ARRESTED, EX-NAZI. When the entities EX-NAZI or DRUG DEALER are actualized as NP; coreferential with NP; (Josef Schmidt), they do not as yet have the status of coreferential entities in the representation. This status will only come about as the result of the explicit 'define'-relation. It is because of this condition that in (30a)—which can be conceived of as an equivalent of (30)—'imperial eagle' cannot be coreferential with 'aquila heliaca':
A. Maes 165
'aquila heliaca' will be available in the text as an NPrNPj'-pair. The same reasoning is applicable to (31) but in a converse relation of dominance. The pragmatic conditions under discussion should be applicable in principle to the so-called defective NPrNP,'-pairs as well, as is partly shown by the experiment of Ortony & Anderson 1977. The adequacy of a metaphorical, 'indirect', lexical NP—as in (15), (16), (39c) and (39c!)—is not only dependent on the question whether the reader is able to identify the intended referent, but also on the relevance and the centrality of the information conveyed by the NP,'.
(42) A woman i was shot in the street. The mortal remains s were quickly removed. The informative value NP,' in (42) can be conceived of as an 'update' of what has meanwhile been said about the dominant entity in the text. Other implicit text relations depend on information about NP; not mentioned in the context concerned but which can be introduced into the context as relevant 'surplus'. This is for instance the case in (43): (43) A woman {was shot in the street. The young woman-twas quickly removed. In terms of representation the difference between 'update' and 'surplus' NP;-, NP,'-pairs can be described as follows: An update NPrNPrpair is the actualization of an implicit text relation between coreferential discourse entities Xj •- y{ in the FS, provided this text relation is dependent on one or more other text relations in the FS x •- z which are the result of an explicit text relation in the TR-component. A surplus NPrNPrpair is the actualization of an implicit text relation between coreferential discourse entities X;«- y; in the FS, provided this text relation is not dependent on one or more other implicit text relations in the FS with x as the dominant entity.
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3.3.2.3 Update vs. surplus NP,' Although some relations (especially of the 'classify' type) may look different, implicit text relations between entities are text-specific. They 'live on' information concerning the dominant entity, information which at that moment is available or relevant in the text. This can be information that has just been mentioned in the text. This is particularly clear in (42), where the relation between WOMAN and MORTAL REMAINS owes its existence to the information given about WOMAN in between NP; and NP[:
166 Coreferential Lexical NPs in Expository Texts
On the grounds of the above, (42) and (43) can be represented as (42a) and (43a): (42a)
TR a. situation (WOMAN, TO SHOOT)
FS
-WOMAN(x)
- DEAD(z) (attribute) 1
b. sequence (MORTAL REMAINS, REMOVE)
b. sequence (MORTAL REMAINS, REMOVE)
WOMAN(xi) 1) follows from T*(i — 1) relative to R (ii) for each S(i) (1 < i m. If one wants to know the order of i relative to m and n, questions such as 'i > n?' can be answered in the following ways (depending on the actual position of i); the answers provide complete information: (i) yes (ii) no, but > m (iii) no, not even > m
(simple answer) (complex answer) (complex answer)
Two essential parameters play a role in Saebo's descriptive apparatus:
In the case of (i) a complex answer isn't necessary because 'i > m' follows from the preassumption that n > m. In the following we will informally investigate factors that guide the construction of ordering relations in natural language discourse. Again we are particularly interested in the flow of information. The segmentation into information units is in many cases just suggestive and should not be taken as implying a definitive solution to the segmentation problem. We will start with a two-element universe of discourse and later proceed to universes that contain more elements. Suppose question Q is asked: Is a taller than b ? Introducing negative answers allows (i 5) and (15'): Text 15: S(i) No, S(2) a is smaller than b. Text 15': S(i) No, S(2) b is taller than a. Since S(2) (in both (15) and (15')) eliminates the possibility that a and b are the same height, the two texts are m-compact. We now change from a two-element universe of discourse to one inhabited by three elements a, b, and c. Our question ?Q now is: Is b taller than a and c ? Potential negative answers would be: Text 16: S(i) No, S(2) b is taller than c, S(3) but (b is) smaller than a.
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(a) the foreground assumption: the 'set of open propositions on which a decision is sought'; (b) the background assumption: it states 'the interdependencies among the prima facie interesting items'.
R. Mayer 185
Text 17: S(i) No, S(2) a is taller than b. Text 18: S(i) No, S(2) but b is taller than c.
Text 19: S(i) b is smaller than a, and/but S(2)
(b is) taller than c.
Text 19': S(i) a is taller than b, and S(2)
b is taller than c.
Text 19' can be used as a verbalization of the position of the three objects relative to each other (the context may be verbalized as 'Let a, b and c be three
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If it is part of the background knowledge S(o) that the heights of a, b, and c are different, (16) and (17) induce the same inference sets. S(2) from (16) can for instance be inferred pragmatically from (17). Assuming S(o), (17) is more compressed than (16). Dropping the information content of S(3) to obtain something like (18) would sound more 'marked': (18) foregrounds S(2) but not S(3) where the latter is supporting information for S(i) in (16). We stipulate in the context of this paper that a text T = S(i) + . . . + S(i)... + S(n) foregrounds all the S(i) (i — 1 . . . n) and the information units S'(i) that are logically implied by S(i) (but no other information units that may be derived from T). We will also say that a is syntactically foregrounded if it occurs in subject position. Foregrounding will play some role in the next example: suppose again there are three objects a,b,c. Let the question ?Q be worded as 'How does b compare with a and c with respect to tallness?'. Text 19 would be a proper verbalization if we assume that a is taller than b and b taller than c. Text 19', however (where a and not b is syntactically foregrounded in S(i) by taking the subject position and where no but as in (19) suggests that the contrast is built up relative to b), wouldn't be appropriate.5 Note that in mathematical parlance a number b is often located relative to other numbers a and c by stating that a < b < c. This mathematical notation is in the service of compression: it is the result of contracting la< b' and lb < c' to 'a < b' (note that in a verbalization of 'a < b < c' respecting the order of the items b isn't syntactically foregrounded).6
186 The Release of Information in Discourse
elements such that...'). Note that an economic verbal ordering of n objects by means of the comparative (excluding the superlative) makes it impossible for all elements to be in syntactically foregrounded positions. Text 20 is for instance pragmatically unacceptable. Text 20: S(i) a is taller than b, S(2) b is taller than c, and S(3) *c is smaller than a (b/a and b).
Text 21: S(i) c is the smallest S(2) b is taller than c, and S(3) a is taller than b. Assuming that the universe of discourse is extensionally available via a background assumption, Text 21 is not m-compact (S(2) can be derived from S( 1)). However, Text 21 provides a non-redundant way of constructing a mental model: first, c is established as the smallest element, then b is linked to c in this model, and finally a can be linked to b. Without S(2) more cognitive effort would be necessary to establish the link between c and b. In (21'), however, this explanation doesn't work. At text time 3 the relations between a, b, and c are already established. S(3) follows from S(i) and S(2) (+background conditions). Note, however, that superlatives foreground elements taking the extreme positions of a scale and are thereby distinguished from non-superlative constructions. This may account for the contrast in acceptability to (20).8
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S(3) contains c in a syntactically foregrounded position. However, S(3) can be derived from S(i) and S(2), which suffice to construct a mental model7 of the positional configuration. Foregrounding c syntactically doesn't license violating the Compactness Principle. Inserting a discourse particle like thus in S(3) would guarantee well-formedness. However, Text (20) would then no longer be an unmarked description but represent the illocutionary force of a deduction. The following text (making use of a superlative construction) has all three elements in foregrounded positions:
R. Mayer 187 Text 21':
S(i) S(2) S(3)
a is taller than b b is taller than c, and c is the smallest.
Text (22) as restricted to S(i) + S(2) documents that not all elements of a comparison have to be named explicitly (the position of b is inferred)—though addition of something like S(3) definitely is not out (on the contrary, with all three elements in syntactically foregrounded positions, syntactic parallelism is achieved).
Text 22 shows that there need not even be an explicit relational link between elements of neighbouring clauses (such that an element of the preceding clause is explicitly taken up in the subsequent clause and related to a new element). This can also be demonstrated by means of (22') where, for instance, the result of spelling out S(2) ('a is taller (smaller) than b') is constructed from information in S(i) and S(2). Text 22': S(i) a is the tallest (smallest) S(2) then comes b, S(3) and then c. Using different linguistic means allows one to create different inferential distributions. We are not permitted to conclude, however, that identity of inferential distributions implies that the same pieces of information are foregrounded. Just compare (23) and (23'): Text 23: S(i) a is taller than b, and S(2) b is taller than c. Text 23': S(i) a is taller than b, and S(2) both are taller than c.
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Text 22: S(i) a is die tallest, (and) S(2) c is the smallest S(3) ((and) b is in between).
188 The Release of Information in Discourse
The two texts have the same inferential distributions; the foregrounding of information, though, is different: that a is taller than c is foregrounded in (23') (after spelling out the pronominal form) but not in (23). Problems of segmentation occur in the following example: our question is whether (24') can be considered an alternative segmentation of (24). Text 24: S(i) a is taller than b and c, and S(2) b is taller than c.
Our implicit assumption so far has been that the S(i) in our texts represent 'atomic' propositions in the sense of predicate logic. In the case of natural language, however, the S(i) are not just 'given' but have to be constructed. Coordination (such as in (24)) provides a non-trivial case. One might for instance spell out S(i) from (24) as two clauses in a syntactic deep structure component or look upon it as one syntactic clause (with constituent coordination) and let construction rules extract two semantic clauses. Assuming that the segmentation of information is strongly determined by surface structure, we accept (24) and not (24') as the proper way of segmentation. (25) will then be eliminated via discourse acceptability principle III, not via Principle I: Text 2 5: S(i) a is taller than b. S(2) It is (also) taller than b and c. Note that there is no discourse particle $ taking the place of also and making (25) appropriate. (26) (or even (27)), though, is possible: Text 26: S(i) a is not only taller than b, S(2) it is also taller than c. Text 27: S(i) a is taller than b. (But) S(2) it is not only taller than b, S(3) it is also taller than c.
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Text 24': S(i) a is taller than b and S(2) (a is taller than) c, S(3) b is taller than c.
R. Mayer 189
Going beyond a three-element universe of discourse will multiply the potential verbalizations. Assuming that a is taller than b, b taller than c and c taller than d, Texts (28) and (28') are certainly not semantically out (28) may for instance be a response to the following question: 'What is the relation of a to b, c to d and b to c with regard to tallness?' However, if we are just supposed to describe the relationship of the four elements where the wording of the question doesn't impose a particular structure, one would rather prefer (for reasons of pragmatic economy) a formulation like the one at the beginning of this paragraph.
and S(3)
b is taller than c.
Text 28': S(i) a is taller than d, S(2) b is taller than c, S(3) a is taller than b, and S(4)
c is taller than d.
The sample presented so far leads to the following general observations. There are a number of heterogeneous factors that guide the build-up of discourse relative to the domain under discussion: (a) the wording of (explicit or implicit) questions that may impose a certain focus structure; (b) the figure-ground-distinction: an object is often foregrounded relative to another object; (c) the possibility of linking neighbouring discourse elements; (d) processing economy. Aspects like those just mentioned can counteract the Principle of Compactness and may lead to a higher or lower degree of compression.
2.2.1 Constructional repair We will now demonstrate the possibility of'repair' as a constructional device in the service of compression. Suppose we have a seven-element universe of discourse {a, b, c, d, e,f,g\, the elements are ordered in decreasing order of tallness. Let's assume we want to know how a, b, c, d, e, and g are ordered relative to f. The following verbalization is rather clumsy in a standard
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Text 28: S(i) a is taller than b, S(2) c is taller than d,
190 The Release of Information in Discourse
situation (something like (29) may, however, be pragmatically acceptable if the S(i) are meant to explicitly specify information for a data base). Text 29: S(i) S(2) S(3) S(4.) S(s) S(6)
a is taller than f, b is taller than f, c is taller than f, d is taller than f, e is taller than f, and g is smaller than £
Text 30: S(i) a, b, c, d, and e are taller than f, and S(2) g is smaller than f. An even more compressed way is provided by Text (31); however, this text allows for the possibility that/ and g are the same height. Text 31: S(i)
All except g are taller than f.
Another (less compressed (?)) version is (32): Text 32: S(i) All are taller than f except g. From a traditional generative point of view of syntax one might conceive of Text (32) as the result of an extraposition from the NP. An alternative account that is more in line with procedural aspects (and thus with the intentions of the present paper) comes from Wittenburg (1987) within a DRT-framework: 'extraposed' phrases are linked to their antecedents in an anaphor-like way, and not, for instance, via something like the (syntactic) slash mechanisms of GPSG, which disambiguate at the level of syntax in order to pave the way for a one-toone correspondence between syntax and semantics. Retraction may even come from the subsequent clause as Text (3 3) demonstrates. Text 33: S(i) All are taller than £ S(2) The only exception is g. The interesting fact about texts like (33) is that the ultimate semantic representation is sensibly achieved by first building up a representation for S(i)
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(30) is more compressed:
R. Mayer 191
and then modifying it according to S(2). Within a framework like discourse representation theory, constructional repair might be simulated in a way to be illustrated below with regard to (34) and (34'): (34) All my friends are taller than Jack, except John. (34') All my friends are taller than Jack. The only exception is John. We would first get a semantic representation like that shown in Figure 1. We would then have to integrate the subsequent information by restricting the content of the antecedent box (Figure 2)? X
= Jack y Friend (y. Speaker)
=>
Taller (y. x)
Figure 1
X,
z
= Jack z = John
X
y Friend (y. Speaker)
=>
Taller (y. x)
Figure 2
M. Krifka pointed out (personal communication) that the notion of 'information unit' could be restricted in such a way that cases of'retraction' do not occur (accordingly, (33)—(34') would consist of one information unit). This view gains plausibility when one takes other cases into account where the unit of informational evaluation is arguably larger than a single simple clause: just think of bi-sentential disjunction where the disjunctive operator is realized in the second clause. Note also that constructional repair as in Text (33) provided by 'exception'-phrases is a local phenomenon: as a rule, correction of S(i) via an 'exception phrase' can come in the following clause at the latest. One of the referees of this paper pointed out that in cases like (33)—(34') the items S(i) are only acceptable with a rising intonation suggesting that the
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X
192 The Release of Information in Discourse
information given so far is not complete and will be modified. This is in line with Frazier's (1985) definition of 'semantic replacement units' that are supposed to be semantically complete. Despite its prima facie plausibility, we will not derive from Krifka's characterization of information units a general strategy how to segment discourse. In particular, there are cases of non-monotonicity where the information correcting S(i) doesn't come up in S(i + 1) but occurs later on. The strategy to accept discontinuous information units can't be condemned a priori but seems not promising if we want to give a procedural account of all the cases where information is retracted.
So far compactness has been regarded as a global property of texts. In the following, a new parameter will come into play. Texts will be evaluated relative to questions, and a new concept of compactness will emerge. We presuppose here the theory of questions as developed by Groenendijk & Stokhof (1984). They define questions as partitions of the set of indices ('possible worlds'), where a partition of a set A is a set of non-empty subsets of A such that the union of those subsets equals A and none of these subsets overlap. A question Q in the sense of Groenendijk & Stokhof is the set of possible semantic answers to Q; each semantic answer is supposed to give exhaustive information. This corresponds to a diagram (Figure 3) where the boxes represent exhaustive semantic answers and where each answer is modelled as the set of possible worlds in which this answer holds. In the context of the present paper we take the modelling of questions as unique partitions for granted (this assumption idealizes reality, because a question may induce partitions of different granularity).
Al
A2
A3
A4
A5
A6
A7
A8
Figure 3
We represent a question as '?Q'; if we want to emphasize reference to T, we write l?Q(T)'; the (true) semantic answer to ?Q(T) will be represented as '!Q(T)'; our texts will be constructed such that !Q(T) can always be constructed from T.
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2.3 Questions and theflowofinformation
R. Mayer 193
We introduce Q-compactness:
the
(equivalent)
concepts
of Q-minimal
set
and
Def. 3: T ' is a Q-minimal set (and thus Q-compact) relative to T and ?Q(T) iff T ' is a text grid of T, T ' implies !Q(T) and no subset of T ' implies
Logical puzzles are usually constructed as Q-compact texts relative to the question that is to be answered: we need all the pieces of information given to calculate the solution. We may give the following example which represents the skeleton of an argument leading up to thesis t: r r-*p (so)p p- t (so)t
Text 35 yields the following Q-minimal sets relative to the question ?c Mi = {r, r -• p, p -• t)
M2 - jp, p - t} M 3 - (t) Note that p, r, and t are supposed to be metavariables; '-•' is to represent a conditional operator but not logical entailmenr, otherwise, for instance, 'r — p' would claim to be a necessary truth, and—with this assertion being true—Mi would no longer be Q-minimal relative to ?t. A particularly interesting kind of Q-compactness occurs if there is an S(i) such that S(i) is Q-compact relative to ?Q(T) (if we conceive of a text as a data base, this would mean that the answer to our question is explicitly stored and need not be calculated). If T is Q-compact relative to ?Q(T), we will simply say that T is Q-compact. It should be noted that each Q-compact text is compact, the opposite, however, doesn't hold. Reducing (35) to (36) (using Mi from above) would yield a ?t-compact text Text 36: S(i) r S(2) r-p S(3)
P-t
However, there is no S(i) in (36) that foregrounds the conclusion t, Thus (37) would be preferred to (36) though it isn't m-compact
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Text 35: S(i) S(2) S(3) S(4) S(5)
194 The Release of Information in Discourse
Text (37) S(i) r S(2) r - p S(3) p - t S(4) (so)t (3 5) is less compressed than (37). However, filling in intermediate conclusions may help making the structure of the argument more comprehensible. Here the remarks on deductively compact texts are pertinent.
Questions may be conjoined. We represent such combinations as sequences ?Q =