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<?xml version="1.0" standalone="yes"?> <Paper uid="C88-1077"> <Title>INTERPRETATION OF NOUN PHRASES IN INTENSIONAL CONTEXTS</Title> <Section position="4" start_page="0" end_page="0" type="metho"> <SectionTitle> 2. OVERVIEW (IF THE PtlENOMENA TO MODEL </SectionTitle> <Paragraph position="0"> This paper is concerned with the interpretation of noun phrases and in particular with NP's occurring in intensional (or opaque) contexts and to the dichotomy existing between value-loaded and value-flee interl)retations. The final goal is to show bow the formalism of lri-eoncepts (introduced in \[Di Euge,tio & I.esmo 87\]), extended in a suitable wily, accounts for tile phenomena under study.</Paragraph> <Paragraph position="1"> Particularly rclovaut iil the present context seem tile works by Fawcett and Hirst \[19861 and Kronfeld \[1986\]. The theory oulined in \[Fawcett & Ilirst 1986\] implies the existence of seven different readings of the sentence (5) Nadia wanls a tlog like Ross's Those readings depend on three different parameters: I) Transparent (de re) vs. opaque (de dicto) II) Source of description (the agent, i.e. Nadia, vs. the speaker) Ill) Time of application (present vs. future vs. repeated) We believe that only three readings are directly related to the informational conleut of the sentence, since neither the source of the description, n(~r the time of applicatiou scent to be among the concorns of the sentence itself. For instance, leawcett and Hirst distinguish betweeu a) Transparent reading, agent's description (Nadia says &quot;I want that dog, which is just like Ross's&quot;. The speaker reports this as (5) perhaps without being familiar wilh Ross's dog) b) Transparent reading, speaker's description (Nadia says &quot;I want that dog&quot;, and tbe speaker, who knows Ross's dog, reports this as in (5)).</Paragraph> <Paragraph position="2"> The problem is that (5) does not seem to be concerned with what Nadir or the spe.'tker know about Ross's dog; it only assumes that &quot;a dog like Ross's&quot; is a description wtlid for the bearer of (5) so that it can enable him to huild an internal representation of what Nadir wants. On the other hand (5) ceaainly involves a description of Nadia's desires; taking this into account, a perspicuous representation should be able to characterize those desires more precisely: Does Nadia wants a dog of a kind that casually happens Io be the same kind of Ross's dog? Or the dog she wants must be of tlnlt kind just because it is the same kind of Ross's dog? In other words how relevant is the description? The relevance of descriptions seems to be one of the central concerns of the work described in \[Kronfeld 86\]. In that paper, a computational model of reference is provided, and definite descriptions outside intensional contexts are considered. Some examples are: s &quot;The conslruction of spaces should not be over-interpreted. They are not representations of realit!C/ or of partial 'possible worlds'. Ill particular, a belief space ('Max believes ') is not a belief or state of belief; at most, it is a way of talk- ing about belief~7\[~conuier 85, p.1521</Paragraph> </Section> <Section position="5" start_page="0" end_page="379" type="metho"> <SectionTitle> 6 &quot;The space elements are not referred to by expressions of language; they are </SectionTitle> <Paragraph position="0"> set up, identified, etc., and may then be used for purposes of reference (or possibly purported reference), tIowever, this distinction has an obvious and yet nontrivial consequence: theories of refarence based on the use of language cannot bypass menhal spaces; they will have to forsake Ihe idea of a direct link between linguistic strectares and referents aod take into account the important intennediate process of space construction&quot;. \[Fauconnier 85, p.158\] (6) Smith's murderer is insane (7) The winner of the race will get $10000 Let's consider ex. (6): traditionally, &quot;Smith's murderer&quot; can be used referentially in ease the speaker &quot;knows&quot; who is the murderer; otherwise, it must be used attributively (i.e. when &quot;whoever he is&quot; is appropriate) 7. Note that, even in case the speaker does not have any clue about the identity of the culprit, still the expression refers to a single, well defined individual. In fact, one of the accomplices of the murderer, after hearing a policeman say (6) on a TV interview, could report that as &quot;Hey, Bob, he told that you are insane&quot;. Analogously, the fact that no winner of the race exists yet does not mean that the reference in (7) is not definite or precise, since the &quot;role&quot; of winner is uniquely defined even when the race has not been run. Again, if Fred wins, it is possible to report (7) telling him &quot;You will get $10000&quot;. Notice, however, that in both examples the reports are correct but not precise, since they fail to convey the &quot;reason why&quot; the thing reported is true, So it seems to us that: in &quot;attributive&quot; readings there is a component of meaning concerning some kind of dependency (Causality?) 8. It is worth noting that this proposal is completely compatible with Barwise and Perry's. In \[Barwise & Perry 83\], in case of attributive reading, the description must be evaltmted in all the situations which contain an individual who matches such a description. That means that the assertion made about tiffs description must be relevant in all these situations. This implicitly states that there is a sort of dependency connection between the description and the assertion, and that this connection is valid in all possible situations which contain an individual satisfying the description. What we aim to show is that the distinction between attributive and referential readings provides us with an important criteriuna that also affects intensional readings.</Paragraph> <Paragraph position="1"> We believe that the two &quot;opaque&quot; readings we envisioned earlier are distinguished by means of the same &quot;relevance&quot; critefium used above. In classical exalnples as (8) Mary wants a dog no relevance criterium can be applied because of the simplicity of the description. In fitct, if Mary said &quot;I want a nice and faithfol animal&quot;, either we assume that, for Mmy, the intension of &quot;nice and f;tilbful animal&quot; coincide with the intension of &quot;dog&quot; (i.e. in all possible worlds the two expressions denote the same set of individuals) or the report is not accurate. On the contrary, we could assume that &quot;a dog like Ross's&quot; is right only in this world (in any world she wants the same kind of dog, which is the same as the kind of dog that Ross owns in this world) or in every world (whichever is the kind of dog Ross owns, in any world, Nadilt wants to have one of the same kind).</Paragraph> <Paragraph position="2"> Let's consider one more example to make the point clearer (see \[Fauconnier 85, pp.45-46\]): - George says: &quot;The winne,' will go to Hong Kong&quot; - The speaker assumes that &quot;the winner&quot; and &quot;the best dancer&quot; are equivalent descriptions (or &quot;equal roles in the speaker's mental space&quot; in Fauconnier's te,'ms) - The speaker says &quot;George thinks the best dancer will go to Hong Kong&quot; We claim that the speaker's report is incorrect (although sincere), contrarily to what Fauconnier assumes, because in an &quot;attitude&quot; context (as &quot;thinks&quot; in the present example and &quot;wants&quot; in the previous case) what must be correctly modelled is the attitude of the agent.</Paragraph> <Paragraph position="3"> The speaker's description always has a subsidiary role: the one of describing correctly the mental state of the agent.</Paragraph> </Section> <Section position="6" start_page="379" end_page="382" type="metho"> <SectionTitle> 3. LAYOUT OF THE SYSTEM </SectionTitle> <Paragraph position="0"> TNs short section provides some information about the overall organization of the system which the semantic interpreter is a part of.</Paragraph> <Paragraph position="1"> The GULL (General Understander of Likely Languages) system works on the Italian language and is based on production nfles. The syntactic structures are represented as dependency trees, where all nodes, and not only the leaves are associated with surface words. For 7 What &quot;knowing&quot; means in the present context is not very clear. If the speaker determined the identity of tlSe murderer by finding his driving license near the corpse and this is the only thing he knows about him, then it can safely be stated that be &quot;knows&quot; who is the murderer, but still the only possible reading is the attri- butive one. s &quot;Conversationally relevant use&quot; in Kronfeld's terms.</Paragraph> <Paragraph position="2"> each subtree-, the root represents the &quot;head&quot; of the constituent and its immediate subtrees are the &quot;modifiers&quot;. The syntactic production rules say how the tree must be extended when a word of a given syntactic category is analyzed (for more details see \[Lesmo & Torasso 83, 85a, 85b\]).</Paragraph> <Paragraph position="3"> As soon as the syntactic rules extend the tree, the control is passed over to the semantic rules: they update the semantic representation according to the meaning of the new piece of tree (in other words, syntax and semantics operate synchronously and the knowledge sources are separate). Backtracking is not used: whenever the analysis is blocked, the current situation is inspected by another set of rules (&quot;restructuring rules&quot;) that modify the dependency tree in order to provide a new interpretation; then, the analysis is restarted on the new tree. Semantically ambiguous words that belong to the same syntactic category ate disanthiguated on the basis of the local context where they appear: no possibility of undoing the choice on the basis of a larger context is currently provided. The antecedents of the semantic rules pick up any newly entered word (the &quot;current node of the tree&quot;) and match it, together with its surrounding context (i.e. its mother node and its dependants), against the domain knowledge, represented in terms of a KL-ONE-Iike semantic net, which fulfills the role of the terminological component in an hybrid knowledge representation system. The access to the net binds stone variables appearing in the antecedent of the rules to nodes of the net (concepts), which are then used in the consequent to build up the representation that is going to be described. Of course, the import of non-content words (as articles and quantifiers) is different from the one of content words. In a previous paper \[Di Eugenio & Lesmo 87\] we described how the introduction of non-atomic nodes called tri-concepts enabled us to deal deterministically with definite and indefinite determiners. Now, we will see how the problems about intensional contexts described before can be solved. In parallel, we worked on quantifiers: some results have been presented in \[Lesmo et al. 88\].</Paragraph> <Paragraph position="4"> Tim semantic representation built by the interpreter consists in two planes (CP: Content Plane; RP: Reference Plane). A third plane is used in the drawings to refer to file stable dmnain knowledge (the terminological component mentioned above, called SP - Semantic Plane). The CP includes a set of nodes and arcs that represent the main assertion and the description of the entities involved in that assertion (i.e. the restrictions imposed on them by prepositional phrases, relative clauses, etc.). The RP contains a set of non-atomic structures called RASs (Reference Ambiguity Spaces) composed of a Concept node, an Extension node, and a Class node (three aspects of a &quot;concepf' that are needed to establish the possible referent of a linguistic expression). These structures will not be used often in the present paper, since they are mote concerned with the representation of articles. A fourth node can be present in a RAS: it represents a subset of the extension and is used when a specific reading is chosen for definite noun phrases. On the contrary, since indefinite determiners are not used in class assertions, the Class node does not appear in RAS's associated with indefinite descriptions. Each RAS is linked to the defining concept of the SP via a SEMREF (SEMantic REFerence) arc. Also in the CP there may appear complex structures (DAS: Distributivity Ambiguity Spaces): They contain two nodes (Set and Individuals) and are used to distinguish between distributive and collective readings. The arc which connects a node in the CP to its associated RAS in the RP is labelled SAME for definite NPs (it simply states that the given node of the CP coincides with the reference node in the RP), I-OF (Instance-OF) for indefinite ones.</Paragraph> <Paragraph position="5"> In order to simplify the figures, we will use the conventions shown in fig.1. Note that the initial representation (as shown in fig.l) will be augmented during the processing of the sentence if the NP has specifications (e.g. adjectives, relative clauses etc.). These specifications are not directly linked to the CP node that refers to the entity but to another node connected to the RAS by a DEF-AS (or NAME, if the specification is a proper noun) arc 9.</Paragraph> <Paragraph position="6"> 9 The introduction of a pair of nodes for a unique referent is justified by the need of keeping apart the entity that partecipates in the main predication and the way it is defined.</Paragraph> <Paragraph position="7"> 4. REPRESENTATION OF INTENSIONAI, CON'FEXTS The main extension to the work reported in \[Di Eugenio & Lesnro II'/l consists in the introduction of CONTEXT SPACES (CS), which enable us to treat the intensional contexts along the lines pro..</Paragraph> <Paragraph position="8"> posed in \[Fauconnier 85\].</Paragraph> <Paragraph position="9"> A Context Space is a subplane of the CP, which contains a set of nodes and of arc connecting them. CS are created when particular conditimm occur ill tile input sentence, in our case the presence of an intensional verb. In this case the CS is created and connected to the node which represents the verb in the CP by a SP-BUtLD (SPace-BUILDer) arc. The fact that the arc leaves a node representing an attitndin;d verb specifies (itnplicitly) the type of the CS lO and its generator. The nodes appearing in a CS refer to entities that do not necessaril7 exist in the enter context (the CP itself is assumed to correspond to the otttennost context, i.e. it contains terms that have to be interptl;ted according to the speaker's view of reality, as expressed in the SP). A node of a certain CS may refer to a local entity ill that CS or to a counterpart in that CS of an entity of tile outer context.</Paragraph> <Paragraph position="10"> The COUNP (COUNmrPart) arc specifies the seeping of nodes in the semantic representation: an mv COUNP that connects a node NI in a CS (say CS1) m another node (say N2) external to CS1 states that N2 is a countt.'tlxtrt of N1 (or, better, of the entity which NI refers to) in the outer t;pace; on the contrary, a COUNP arc staldng from N1 and entering N1 itself specilies that NI has no counterparts th outer contexts, i.e. it refers to a local entity of space CS1. The absence of a COUNP ace leaving from NI represents art ambiguous case in which tile scope of N1 has not been determined yet. Such ambiguous representation enable us, as we will later see in the paper, to develop a determitfistic attalysis of sentences also in case of de-re or de-dicto ambiguity, Let's show how these struclnres are nsed by means of some of tile previotts examples. During the interpretalion of sentence (5) the analysis of the fl'agntent &quot;Nadia wttttls&quot; leads to the creation of a new CS (CS1 in fig.2). CS1 represents tbe &quot;world of Nadia's desires as mentioned iu the sentence&quot; and is linked to node N2 (instance of &quot;to want&quot;) tlmmgh a SP-BUII.,D arc. Node N3 represents what Nadia wanls as an instantiation of the &quot;dog&quot; concept and is introduced in CS1 when &quot;a dog&quot; is analyzed. Up to this point, lhe representation must be considered as atnbiguous, sitlce it does not specify which is fire status of N3 wilh respect Io the speaker's world. In case no further processing is possible, then tile sentence remains ambiguous (fig.2 shows the basic ambiguous representation of sentence (5)); in other cases, perhaps depending on the context where tile sentence is uttered, it could be possible to decide whether tile intended reading is 10 Ill Ibis pallor we will only deal with &quot;attialdinar' CS's. Actually many oth-Er types of C~;'S may be used to cope with other kinds of linguistic pitettorttclta, For example a &quot;temporal&quot; CS may be used to deal with tile antbiguity of &quot;In 1970, tile president met my sister&quot;, where &quot;the preside~lt&quot; could refer either te tile current president or to file person who was president in 1970. &quot;de-m&quot; or &quot;de-dicto&quot; (also preference criteria could be adopted; for instance, it seems that, outside any specific context, the preferred reading of (5) is the intensional one); when such a disambiguation is possible, then the representation is expanded by including a suitable COUNP arc: it will leave fi'om node N3 and will enter node the same node N3 iu case the reading is intensional, otherwise it will enter a newly-created node outside CSI (tile latter alternative is reported in fig.3). It is clear that it is the presence of node N8 that relates tlae representation to tire existence (in the speaker's world) of a specific entity wanted by Nadia, contrarily to what happens in the intensional reading, where no node (referring to a dog) existing outside CS1 is linked to N3.</Paragraph> <Paragraph position="11"> As stated above, two different &quot;intensionar' readings can be obtained for sentence (5) depending on the relevance of tile description. The representation we obtained till now corresponds to the purely referential l'eading of (5) (actually, this use of &quot;l~eferential&quot; is slighhy inappropriate, but the previous discussion should enable tile reader to intmpret it correctly). If we want to represent the &quot;attrihitrive&quot; reading we tnust add something to the Stl'tJcture; what we need is a specification of the &quot;dependency&quot; of the statement made through the utterance on the description used. To this aim we include the WIllS (WH-ever IS) arc, as shown in fig.4. At this point, the import of this arc shotfld be clear.</Paragraph> <Paragraph position="12"> The proposed formalism enables the system to operate deterministically, i.e. to build the liual representation without destroying strttctures built previously (this was one of the goals of the introduction of tri-concepts, as explained in \[Di Eugenio & Lesmo 87\]). In fact the system builds a basic ambiguous representation (as shown in lig.2 for sentence (5)) which is possibly expanded with the introduction of new arcs when sotne disantbiguation is possible. Of course, the insertion of suitable arcs does not modify the set of nodes initially stored in the CS's, which remain stable (perhaps expanded) throughout the analysis. As regards the disantbiguation criteria, it does not seem that there are general roles for choosing one interpretation or tile o/her. Of course, if the verb does not open an intensional context, then no problem arises (the CS is not created) Jr; On the contraly, if we consider a verb as &quot;seek&quot;, it sectns that only the object NP can provide the clues to select one particular reading; in &quot;Mary is seeking a street&quot;, the preferred reading certainly is non-intensional; in &quot;Mar5' is seeking a fl'iend&quot; still seems to be preferable to assume the existence of a ptu'ticular fliend; on the contraly, in &quot;Mary is seeking a ftmding&quot; there seem 1o be few doubts thai the funding does not exist yet. We are currently trying to build heuristic roles, based on nominal hierarchies appearing in the terminological component of an hybrid knowledge representatiott formalisnt, able to suggest a particular reading. Moreover, subsequent sentences may provide further disantbiguation criteria. Consider the example in \[Fauconnier 851, peg. 57: (9) Ursula wants to marry a ntillionaire.</Paragraph> <Paragraph position="13"> We nnty obtain different readings depending on the subsequent sentences: null (t0) lie is really a eon-nlan leads to a de-re (referential) interpretation, while (11) But she won't thld one indicates a de-ditto reading tbr sentence (9).</Paragraph> <Paragraph position="14"> A linal point concerns the use of the proposed representation in the subseqttent phase of irtterpretation. Generally, the search for tile correct referent in the discourse history is led by the presence of a RAS in the RP and by its incoming (I-OF or SAME) and outcoming (a DEF-AS arc which connects it with the representation of the referent's description) arcs. An indefinite specific reference (for exatnple &quot;a dog&quot; in &quot;a dog is eating meat&quot;) causes the creation of a new entity, since the assumption is that indefiuites are used when the referent is not identitiable by the reader. On the contrary definite specilic reference (for example &quot;the dog&quot; in &quot;the dog is eating meat&quot;) leads to the search.for the entity referred to into the discourse history l:~ n Actually, the verb of the sentence is exatnined in all cases, since tile presence of some auxiliaries folx;es the creation of an intensional context; consider, for iastaoce: &quot;You tllusl reserve a seat&quot;, &quot;I will build a lable&quot;. Of course, these verbs, when used in the past tense do not have any intensional characterization.</Paragraph> <Paragraph position="15"> l:~ Obviously, many other types of references are possible* For a complete analysis of referential problem connected with tile semantic of determiners see \[Di Eagenio & l~esmo 87\], Let us see now the impact of the newly proposed extensions onto this environment. When a RAS is referred to by a node Nk through an 1-OF arc (indefinite specific reference) the possible presence of Nk in a CS (say CS1) may be detected. If this is the case, node Nk must be inspected: if it has a COUNP arc, pointing to a node of the external context, then the usual creation process is executed; otherwise Nk refers to an entity which is local to CS 1 and has no counterparts in the external worid. So we need an interpretation which blocks any infet~ence on the entity associated to the node in the external world. This result can be obtained by copying the whole CS in the Iinal network representing the discourse history, and so biding its internal node to the external context.</Paragraph> <Paragraph position="16"> Let us specify now the interpretation of the WHIS arc. As stated above, when a RAS is refetTed to by a node Nk through a SAME arc (definite specific reference), an entity satisfying the description (represented by a Nj node of the CP connected to the RAS through a DEF+AS arc) is searched for in the discourse history network. In fact, in this case, we only have to cope with &quot;the functional relevancy of the description&quot; \[Kronfeld 86\] (i.e. its ability to convey infolxnation leading to the identification of the correct referent). But what does it happen if we also have to account for conversational relevancy, i.e., what is the interpretation if a WHIS arc connecting the description node Nj to the node Nk exists? In this case the usual searching for the referent is delayed. Both node Nk and its description (represented by the WHIS ate and by the subnet of CP whose head is Nj) are entered in the discourse history network.</Paragraph> <Paragraph position="17"> In this way the description itself becomes part of the final representation of the sentence (as stated in \[Barwise & Perry 83\]). Moreover the presence of an arc WHIS in the final network states that the node entered must not be considered as the referent of the sentence hut rather as a &quot;role&quot; (see \[Fauconnier 85\]) which may assume different values in different worlds (i.e. in different CS's). In fact, different referents for the descriptiort may be detected by the usual searching process in the CS's and this leads to different inferences (different assignments of referents to the &quot;role&quot;).</Paragraph> <Paragraph position="18"> A final remark is needed: for the sake of simplicity we stated that the relevancy of tile description must be detected during the analysis of the input sentence, independently from the subsequent interpretation process. Actually the strategy of the system is quite more flexible, because also the interpretation process, merging tile semantic representation of the sentence and the discourse history network, supplies further information about the relevancy of a given description. For example, when the sentence does not include sufficient information to choose between referential and attributive reading), the absence in the discourse history of a referent litting the description (detected during tile final process of interpretation) forces an attributive reading.</Paragraph> </Section> class="xml-element"></Paper>