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<Paper uid="C96-1065">
  <Title>Discourse Semantics Meets Lexical Field Semantics</Title>
  <Section position="3" start_page="0" end_page="777" type="metho">
    <SectionTitle>
2 DRT -- Inferentially Motivated
</SectionTitle>
    <Paragraph position="0"> Discourse RepT~sentation Theory (DRT) is first and foremost a theory about discourse interpretation, i.e., it is essentially textually oriented in natm'e. The meaifing of sequences of sentences is seen as strongly connected with their  inferential behaviour. Therefore, work on lexieal seinantics in tile Dll2F frmneworlC/ ((Kam I) and Rofldeutscher, 1994a); (Kamp and Rotldeutscher, 1994b); (ll.otadeutscher, 1994)) investigate.s the role of lexieal information in supporting inferences. Consequently, lexical distinctions correlate with non-equiwflent sets of associated inference.s.</Paragraph>
    <Paragraph position="1"> The following ('.xalnt)les illustrate that the German verb leihen (in its variant to lend) implies in (:ontrast to the German vert) versehenken (in its variant to give as a present) the lending t)erson's belief in a return of the involved object,: (la) Calvin lciht IIobbes eine Krawatte.</Paragraph>
    <Paragraph position="2"> (Calvin lends Hob/)es a tie) (lb) Calvin glaubt, daft \[lobbes ihm die Krawatte zuriick.qeben wird. (Calvil, believes that th)l)l)es him the tic will give t)ack) (2a) Ualvi'n versehe'nkt ei'n Hueh an Hobbes.</Paragraph>
    <Paragraph position="3"> (Calvin giw'.s as a 1)resenl; a book to Hobbes)  (2b) Calvin .qlaubt, daft Hobbes ihm alas Buch zuriickgeben wird. (Calvin believes that Hot)bes him the. I)ook will give 1)aek) \[n line with the ret)resentation format (Icy(lolled by Kanlt) and l/,ot.~deutseher, the corresl)onding lexieal entries are, twofohl stru('.tures: They (',onsis(; of a I)resul)l)ositional and an asserlx)ric Diseo'wrs(&amp;quot; l~cpresentation Structure (I)R,S). Th(; underlying anat)horie notion of presul)position was originally t)roposed by (Sand(, 1992). Presupl)ositional information is embedded in the discourse eontext by a process called justification, whi(:h (:omt)ines 1)inding (veriJication) with contextual (mri(:hment (accommodation) in varying prol)ortions.</Paragraph>
    <Paragraph position="4"> Kamp and I/.o\].~dcutscher model the inl;erface l)e~ween syntactic and semanti(: al'glltrlents as a list of t)airs. Each pair consists of tim generalized case information and the eorresl)onding the-. matic role of the m'gulnent slot under eonsi(leralion. This mapt)ing offers two starting points for an integration of DRT and SET.</Paragraph>
    <Paragraph position="5"> Firstly, the representatioi~ format fin' the generalized case information is only sketche(l, an algorithm for case assignment is not given: With each verb is associated a .(liven set of so-(ailed theta roles Oi. These theta roles are arran.qcd in a fixed hierarchy, the theta-hierarehy. \[...\] Those argument phrases wh, ich get assigned a theta role also get assigned a particular case (Nora, Aec, (etc.).</Paragraph>
    <Paragraph position="6"> \[...\] Case assignment is partially determined by kit(', theta hierarchy in that the argument phrase which bears tit(&amp;quot; highest theta role (in th&lt;' sense of this hierarchy) always gets nominative case.</Paragraph>
    <Paragraph position="7"> ((Kamp and l{ot.kleuts(:her, 1994a): Pl). 109f) Secondly, the thematic roles are specified individually for each lexical entry, there in no get&gt; eralization with respect to lexical fields. As an example, the. interface list of verschenken is given ill Figure 1, where the eompoimllts of each pair m'e displayed vertically.</Paragraph>
    <Paragraph position="8">  The, discourse referent ec and the thematic roles of the. interface, are. direct links to the DR, S ret)-resenl;ing the hi(airing of the German verb yew. schenken (of. Figure 2). The event comi)lex ec, whi(:h stands tor the verb itself, in described as a process e, which is caused by an action e* of a person p. p tel)resents l;he one wit() gives the t)resent u to ;mot, her person q. The giving itself is (:hm'aeterized by the concept (HIAN(IE-SIGN. The signs changed are those of the disi)osal and owner-ship relations So and sl: p looses the disposal and ownershi 1) of u and q gains them. The former cir(:umstances of disposal mid ownershi t) (so and ,st abut on ee: ,So ZXZ e.c .sl 73(2 eel m'e t)resut)t)osed , the t)ost, statcs (ce bC s2 ec ~ sa) are asserted.</Paragraph>
    <Paragraph position="9"> 12(: t) q 8 2 S 3 1l</Paragraph>
    <Paragraph position="11"> The (;xarnt)le inf('a'ences (la) to (lb) and (2a) to (21)) result froln differences in the lexical DlI.Ss of leihen and verschenken. The main t)oint here is that tllo. (.;elInan vei'l) leihen intt)lies the lending t)crson's belief in a l'eturn of the involved object.</Paragraph>
    <Paragraph position="12"> On the basis of (;his belief it in easy to inR.'r front (la) to (lb). ltowever, there is no similm' SUl)I)ort for inferring from (2a) to (2b). A detailed lexical representation of leihe'n will be given in section 4.</Paragraph>
  </Section>
  <Section position="4" start_page="777" end_page="777" type="metho">
    <SectionTitle>
3 SET - - Lexical Field Based
</SectionTitle>
    <Paragraph position="0"> Semantic Emphasis Th.eory (SET) has identified princit)les that allow to link a prototypical description of a situation to a number of prototypical meaning descriptions of con(:rete lexeines  that; are suitable to refer to that situation. The link is based on a set of well-defined and systematically occurring mappings (cf. (Firzlaff and Kunze, 1995)) rather than on intuitive criteria. Given a basic semantic form (BSF) as a cornmon starting point, we derive semantic and syntactic case frames and construct prototypical meaning descriptions of concrete lexemes by refining the BSF. Additionally, the rule based interpretation of a BSF delivers a prototypical description of the corresponding situation.</Paragraph>
    <Paragraph position="1"> The set of lexemes that are suitable to refer to the same situation constitutes a lexical field. The field as a whole is characterized by a BSF. A BSF is a propositional description. It consists of a predicate and a nmnber of arguments, each of which is either a predicate-argument structure or an elementary argunlent. In general, elementary arguments are represented by variables that have to be filled in by phrases which denote reference objects (participants of a situation).</Paragraph>
    <Paragraph position="2"> The number of arguinents, as well as the decision whether the arguments are elementary or propositional, both depend on tim predicate that, directly takes these arguments. We derive the participants' ttminatic roles (deep cases) in accof dance with a set of general rules. Semant;ically, each pair of a role and the predicate directly dominating an elementary argument demands particular selectional features for that argument. The BSF describing the field of change-of-possession (with one object to be transihrred) and the derived deep cases are given in Figure 3.</Paragraph>
    <Paragraph position="4"> From both the syntactic and the semantic point of view, the BSF delivers the maximum case frame of the lexemes that constitute the lexical field.</Paragraph>
    <Paragraph position="5"> Some of the roles of the maximum case frame can be put into the foreground; these are said to have cmphasis. Some roles nmst not be verbalized explicitly; these are said to be blocked. In the subset of roles that are not blocked there are, on the one hand, roles referring to obligatory actants and, on the other hand, roles referring to optional actants.</Paragraph>
    <Paragraph position="6"> Which roles have emphasis and which do not have emphasis, which are the ones that must be verbalized, and which are the ones that need not be verbalized is determined according to general rules.</Paragraph>
    <Paragraph position="7"> Exploiting the field specific possibilities to make some variables denote the same reference object (by renaming of variables) results in more specific BSFs. These then describe partial lexical fields like, e.g. to give or to take.</Paragraph>
    <Paragraph position="8"> By adding infbrmation about, emphasis and blocking of roles, a BSF is transformed into a number&amp;quot; of prototypieal meaning descriptions. We can then derive systematically which are the suitable grammatical realizations of each role. However, there are two important points concerning the determination of which grammatical realizations are possible: Firstly, the predicate that takes the corresponding elementary argument directly and, secondly, the choice of that subset of roles of tim maximum case frame that are not blocked. One of the three prototypical ineaning descriptiolm that constitute the partial field of to 9ire and tile gramrnatical case assiglmmnt of verschenke,n 1 is given in Figure 4. (Those parts of l;he description t;hat have emphasis are written in bold face. Tile occurence of a variable preceded by &amp;quot;T&amp;quot; is blocked. The grammatical realization of the optional actant (an+accusative) is put, in brackets, z)  grammatical case assignments.</Paragraph>
    <Paragraph position="9"> However, BSFs do not only provide the ground for the derivation of grammatical features. They are also suitable to derive prototypieal situation descriptions. In order to do so, instantiation rules must be applied to a BSF in a recursive way.</Paragraph>
    <Paragraph position="10"> The application of instantiation ruh;s has to be regarded as an interpretation of every partial description in a BSF. Some of these parts are, then represented by variables that have to be filled in by objects referring to states or (;vents, and other parts deliver relationships between these states or events. In addition, some of the instantiation rules provide temt)oral and/or spatial constraints that are applicable to (tim corresponding parts of) a prototypical situation description, e.g., etimc is a mapping fl'om the set of events or states to the set of temporal entities (etime: g -+ T).</Paragraph>
    <Paragraph position="11"> In general, tile instantiation rules provide struc1Generally, this grammatical case assignment is suitable for about 20 verbs of the partial field to give. 2More precisely, there is a mapping front the set of variables into the set of nominal phrases (more generally, parts of speech) f: V --+ b r.</Paragraph>
    <Paragraph position="13"> t)redieate BEC: I1; has one mgmnent whi(:h is ~ t)redieate-.a.rgunw.nl,-strucl;ur(~. This sl;ru(:l;ur(~ is 1;o tie inl;ert)rel;e(1 &amp;s the finnl sl;a.l;e of ;1 tra nsil;ion. Because of the insta.n|;iation rule of BEC the initial state (init(e.))of the l:ra.nsition (c)is l;he &amp;quot;()t)t)ositC' of the final state (fin(e)), i.e., BEC(A) is inl;erpreted as c: TII.ANSITION (~A,A). According to (aUilg 3,1l(1 Kiistne.,', 1q90), init(c) (i.e. ,At is I;11(; 1)resul)t)osition of c, and &amp;quot; ,&amp;quot; does not; ;ffl'e(:t A's t)resut)l)osition, e.g. seh~cA;iotm\[ restrict;ions for A's elelnenl;&amp;ry arguments. A more (~xtensive ex-.</Paragraph>
    <Paragraph position="14"> mnl)le, of the d(wivation of t)i'ol;otyl)i(:;d sil;ua.tion des('.rit)l, ions is given in Figure 5? The situai;ion 1)rol;ol;yl)i(:Mly th~s(:ribe(t in Figllre 5 (:all 1)e reDrred to by al)Otll; 65 (~ertmm verlts, i.c.., the elements of the partial fM(t to give including our samph~ verbs vcrschc.nkcn (in its w~ri;mt to .qivc as a p'rescnt;) and h:ih, cn (in its vm'iant to h'.nd). As far as the degree of speeifieal;ion is (:on(:erned the des(:rit)i;ion is at leas(; suil,able as (:ommon d(mominator. Since SET's l)rineipal oriental;toil is l;owaa'(ls the systemal, i(: des('ription of le~cical fields rather than of single lexi(:al entries, it provides ret)resentations whit:h tend t;o 1)e mtdersttecified with respect to e.g. Dll\[\[&amp;quot;s requirements. However, due to SITI&amp;quot;s gener;,l eq)pr()ach mty fltrther spe(:ification of its (h~s(:rif)l;ions lea(Is to an enlargement of the ret)resental;ion r~ther t;h;m to tt change of the common denominator. The (les(:ril)lions i)rovided by SET are suitable as the basis for fine grained representations. Theretbre, one can expmM the lexicM enl, ries rather (;turn (:onstrut:ting l;heln ea(;h and every time flom s(;ral;('h. TO exentl)lify l;his, in the next secl;ion, the ret)resentatioll of lcihe'n (in its w~ria,nt to Ic'nd) is emiched by the hmding ltel'SOll'S belief in a return of t, he involved object.</Paragraph>
    <Paragraph position="15"> aref(f(x)): V -~ .7 -+ 1). And 7) is the set of rel~rence objec|;s.</Paragraph>
  </Section>
  <Section position="5" start_page="777" end_page="777" type="metho">
    <SectionTitle>
4 The Puzzle Fits
</SectionTitle>
    <Paragraph position="0"> Based on the hypothesis that: SET's proi;ol;ypical situation descriptions ca.n be interl)reted in the same way as 1)l/Ss we have l)ro(:ee(led to a new joined ret)resentation format. Since w~riabh~s in a I{SI&amp;quot; have to 1)e filled in l)y r('.ferenc(~ objects and, fltrtherm()re, the rtR;llrsive ;q)t)li(:al;ion of insl.m&gt; tiation rules provides wu'iM)les of the stone kind \[*Of eVOlI\[;S &amp;Ild SIALI;(~S, S\]~r\[&amp;quot;S l'efereiIce o})je(',(;s }l.lt(l l)l{T's discourse referents are reg~r(ted as etlUiV-M(',nl; metals of (!Xl)ression. Tlmreli)re, the joined l(~\[)l(iSelll;aA;i()li fOl'llt3\]; ltses I)I/\[F's boxes, llowever, it is enriched witih among others, n revised inLerI, tt:e I;() syntax where the thematic roles m'e derived according t;o lISFs.</Paragraph>
    <Paragraph position="1"> The sample rel)resent&amp;tions giwm in Lhis section exploit Karat) a.nd \]{ofideutsc.her's idea of h'.x ical axioms (of. (Karat) ~md l{.oB(h~uts(:her, \] 994a); (Kaml) and l{oBde.uts(:her, 19(,)4t)); (Ro\[/d(!ul,seher, 1994)). We (:~i1 ~ (lis(;inguish in a l);4ra, ltlet;ri(; fas\]tion between I;11(; s('an;mti(: (:Oml)onenl;s of 1;t1(! en-Lries that (:hma(:|;(wiz('. (pnrtia\]) lexi(:al \['i(;l(ls and the (:on(:et)t si)e(:ific inf()rnt~tion in i;he axioms.</Paragraph>
    <Paragraph position="2"> The first pair of axioms introduc(;d below mir--I'OI'S l;he fact tlud; the configuration a l)brevialxxl by eu: (cul ,cue) (ef. Figure 5)is suitabh~ I:o spec ify a wlriety of h',xica.l fMds wherein the s('ammti(:s of the (~lenw.nts inv()lves a sl)eeinl kind of '(:han/~e'.</Paragraph>
    <Paragraph position="3"> Some exalnples of these fMds are ch, angc-@placc (e.g. to travel fro'm o'nc plat(&amp;quot; to another), cha'ngcof-class (e.g. to promol, c somebody to a certo, in rank), &amp;quot;,rod changc-@posscssior~,. Ae(:()rdingly, we t)roltose a predicate hierarchy, wheret)y the i)re(li(;~tes PI,ACI,;~ \[SA~ \[lAVE ~:~\]e st)ecializations of the I)re(ti(:ate STATE. Note, however, that 1;his does not affect the ine(:hmdsm of role deriva.|;ion 1)reseilte(l in section 3.</Paragraph>
    <Paragraph position="4"> In the t)rototyI)ical sit;m~tion des(:rit)tion ((:f. Figure 5), (,'e inchMes eel a.nd c~2. F,a.(:h ()f' Lhese (10,nol;es ;1~ TIIANSI'I'ION tl()IIl tttt initiM st, ate to a. final state, i.e., from init(s,e:L) and inil,(c.e2) (the presupposition) to Ji'n(e.2t) m,d Jin(c.2.~) (the  assertion). Because of the temporal identity of e21 and e2~, there are temporal overlaps between the initial states as well as between the final states.</Paragraph>
    <Paragraph position="5"> In the axiom defining CHANGE-SIGN's prestate, so's consequences sl and s2 correspond to init(e21) and init(e22). In the axiom defining CHANCE-SIGN's result state, s0's consequences st and s2 correspond to fin(e~:t) and fin(e22). The axioms have in common that they involve the concept CIIANGE-SlC, N (cf. c2 in Figure 5). The axioms are given in Figure 6 (&amp;quot;O&amp;quot; denotes temporal overlapping).</Paragraph>
    <Paragraph position="7"> The concepts defined by means of these axioms are, then, used to specify the lexical entry of verschenken (in its variant to (live as a present). The thematic roles and the corresponding grammatical realizations result from the derivation presented in section 3. PRE(CHANGI,2-SIGN) delivers the first part of verschenken's presupposition. The parameter STATE is filled in by DISP&amp;OWN which is added to the predicate hierarchy sketched already as a specialization of the predicate IIAVF.</Paragraph>
    <Paragraph position="8"> Thereby, it is possible to distinguish between the pure disposal and the disposal thai; is accompanied by ownership.</Paragraph>
    <Paragraph position="9"> Furthermore, verschenken's presupposition includes the semantic roles delivered by its prototypical meaning description. However, the selectional restrictions for discourse referents do not differ from the restrictions given in the prototypical situation description (cf. Figure 5). With respect to the semantic interpretation, each of source-have, goal-have, and locat-have just means is suitable as first ar.qument in a IIAVE-proposition. Generally, the predicate directly determines the selectional restrictions of its arguments, i.e., the discourse referents. Furthermore, for those predicates that take more than one argument, it is the order of the arguments which additionally determines the selectional restrictibns. 4 In accordance with the prototypical situation description given in Figure 5 the DRS for verseheuken is as follows: 4Clearly, these are .iust two pieces of information for the seleetional restrictions.</Paragraph>
    <Paragraph position="10">  The entities constituting ec (the action, the transitions, and the causation) are located in a common time span. Therefore, the transitions' initial states precede ec (so ::)(7_ ee) and the transitions' final states follow ec (ec DC st).</Paragraph>
    <Paragraph position="11"> The lexical entry of leihen (in its variant to lend) consists of an interface list, whose thematic roles are based on SET, and of semantic structures, which include and extend versehenken's semantic components. The inferential behaviom' of leihen (exemplified in section 2) motivates a forreal description that contains more than the basic distinctions provided by the partial lexical field to give. Additionally, there is the lending person's belief in a return of the involved object, in other words, the belief that the CHANGE-SIGN from s o to s~ is temporary. Therefore, leihen's representat, ions make use of CIIANGE-SIGN's subconcept CIIANGE-SIGN-TEMP. This subconcept entails ;t transformation of its superconcept's prestate So (so DC ec) to its superconcept's poststate s~ (ee DC sl) as well as the new poststate s2 (ec ~ s.e), i.e. the belief in a return of the involved object.</Paragraph>
    <Paragraph position="12"> ec: leihen</Paragraph>
  </Section>
  <Section position="6" start_page="777" end_page="777" type="metho">
    <SectionTitle>
\[ NOM DAT ACC \]
</SectionTitle>
    <Paragraph position="0"> &lt; agens, act &gt; &lt; goal, have &gt; &lt; to - obj, have &gt; Figure 9a. Interface list of leihen's entry.</Paragraph>
    <Paragraph position="1"> To nmke the description of leihen complete, a further lexical axiom which explicitly notes the belief in a return of the involved object is ne6ded.</Paragraph>
    <Paragraph position="2"> One of the formal means provided by DRT is the possibility to model components of psychological  attitude states, e.g. beliefs or desires (of. (\[q'aCaS-D8, 1994)). ~ p q ,, .~,</Paragraph>
    <Paragraph position="4"> Figure 9b. Semantic structures of lcihcn's entry.</Paragraph>
    <Paragraph position="5"> This possibility can be used to state the axiom which represents the specific semantic contribution of C\[\[ANGE-SI(IN-TEMI': it, s poststate ehara(&gt; terized by the state s2 of the person r0 being in an psychological attitude state one of whose coinponents (c) is a certain belief. This belief consists of an inversed (\]IIAN(;I,;-SI(-\]N-eVeIIt C, i.e. a return, with its resulting disposal (:onfiguration sa. Thereby, the forlner circumstances of disposal Sl, that result fl'om the CIIANGE-SI(IN-TEMP-evenL itself, are supposed to abut on the return event c.</Paragraph>
    <Paragraph position="6">  On the one hand, these results mark directions tbr the developme, nt of a comprehensive lexical theory, that include, s, for example, an elaborated concept hierarchy with associated axioms. On the other hand, they (:an be used for a detailed reconstruction of the inferences inentioned in section 2.</Paragraph>
  </Section>
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