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<Paper uid="C96-2144">
  <Title>A Constraint-based Case Frame Lexicon</Title>
  <Section position="3" start_page="0" end_page="854" type="metho">
    <SectionTitle>
2 Representing Case Frame
</SectionTitle>
    <Paragraph position="0"> Information In rlhu'kish, (and possibly in many other languages) verbs often convey several meanings (some totally unrelated) when they are used with subjects, objects, oblique objects, adverbiM adjuncts, with certain lexical, morphological, and semantic features, and co occurrence restrictions. In addition to the usual sense wu:iations due to selectional restrictions on verbal arguments, in most cases, the meaning conveyed by a. case Dante is idiomatic, with subtle constrMnts. For example, the Turkisln verb ye (cat), when used with a direct object noun phrase whose head is:  1. para (money), with no case or possessive markings and a lmman subject, means to accept bribe, 2. pare (money), wittn a non-human subject, means to cost a lol, 3. para (or any other NP whose head is ontologically IS-A money, e.g., dolar, mark, etc.) with obligatory accusative markilig ~md optional possessive meriting, means to spend *~IO~tCy~ 4. kafa (head) with obligatory accusative marking and no possessive marking, means to get mentally deranged, 5. hak (right) with optionM accusative and possessive markings, mearls to be unfair,</Paragraph>
  </Section>
  <Section position="4" start_page="854" end_page="854" type="metho">
    <SectionTitle>
6. I~(t.s( (head, of'. d) (or a.ny N\] ) whose het~(/
</SectionTitle>
    <Paragraph position="0"> is ontologically IS-A hnma.n) with optional accusative mill optio,al i)ossessivc marking (obligatory only with ba,~), lilea31s lo waste or demote, a person.</Paragraph>
    <Paragraph position="1"> On the other ha.rill: I. if' a.n ablative ease-marked oblique object deuoting ;m edible entity ix present, then there should not be any direct el)jeer, a.,d tile verb ,,w:m,s to eat a 1,ieec oJ&amp;quot; (the edible (oblique) oD\[\]eet)l or 2. if the abla.tive case-ll,au'ked oblique o|)ject does not denote something edible, but rather a. container, then the sense maps to to eat oul of, with the optio'naldirect (cdil)le) ol)ject denoting the ol).iect eat(,,.</Paragraph>
    <Paragraph position="2"> Ctea.rly such 11sage ha.s impas:t on tln'Jnatic roh: nssigmn(;nts to va.rious role fillers, a.nd even (m l.he syntactic Imhavior of the vcrl) in question (lh'iscoe and (;a.rroll, 1994). I&amp;quot;ol: iustance, for the third a.nd l'om:th ca.ses ~d)ove where the ob,i('~ct has to b(; ol)lig;d, orily case-marked ~c('usa.tive, a. lmssive form wouh |not be grammatical fi)r the sense convey(',d, ?all;hough syntactic;ally yc (eat)is {t transitive verl).</Paragraph>
    <Paragraph position="3"> Soruetimes verbs require diilhre, nt co,nbin~ttions Of o, rglll\[lellts~ or explicitly require tha.t certa.iu argumonts ,,ot I)e present. For insta.nce, the verb qa~ requires ditDrent kinds of argunnmts del)endi,g (m the sense, obligatorily exel uding other argmnents: I. a.n ablative casc-ma.rked oblique objcel and with no other object, in tim ca s(', f,'~mw. ~aq llle;I.ns to devialc J'rom,  2. a, dative case-marked oblique object and with uo other object, ~a~ menns to be s'a'lT~riscd at, 3. ~m accusative casc-mar'ked direct object with no other objecl, qaq llleg-ms lo be cocO:used aboul.</Paragraph>
    <Paragraph position="4">  As ~ |iual examl)\]C, when the verh lul (ca.tch/hohl) is used with a.. obligalor:q 3 ~'d per-son singular agreemenl ;rod active voice, and the subjeel is a Otominalized) ,5' with a verb form or future parliciplc, then the sense conveyed by the top level ca.se frame is to \]?el like doinq the predication indicated by the subject S's case \['r~mte, with the agent being tile subject of tiffs embedded chmse. As illustrated in these examples, verb sense idio.m~tic usage resolution h~ts to be (lea, It with in a. principled way and not by pnttcrn nmtching (e.g., ~s in 'l'schichold (1995)), when the l~mg, u~tge has a free word order, where l)~l, tern matching al)pronchcs could 5dl. In this p~q)er, we present a unification-based apl)ro~wh to ~ constraint-be.seal case fra, tne lexicon, in which one single mechanism dee.Ix with both l)roblents mtil'ormly, q'hc ess(.nti~d function of our lexicon is to m~q) bidirectionally I)etween a, case frame containing information that is sy~fl;acti&lt;', and ~ sem~mtic Dame wifich c~pl, ures the predication denoted by the case fr~mw along with information ~d:)out who fills what thematic role in that predication.</Paragraph>
  </Section>
  <Section position="5" start_page="854" end_page="858" type="metho">
    <SectionTitle>
3 The Lexicon Architecture
</SectionTitle>
    <Paragraph position="0"> In this section we present nn overview of stru(': ture of lexicon entries m~d the nature of the consire.Juts. 'Fhc basic unit in the lexi(:on is a sense which is the inforlm~tion denoting some indivisible predication along with the thematic roles involved.</Paragraph>
    <Paragraph position="1"> We generate the (:axe frame of each sense hy uni\['yiug a set of co-oeeurrelme, morphological, synt~tctic, semantic, ~md lexieal constraints on vert)s, their ~trguments. '\]'he lexicon is implemented in TFS (Kuhn, 1993) by the disjunction of the senses defined by unifying wf-case-frame (well-formed ca.so frnme) with each sense: wf-case-fra~m &lt; case-flame.</Paragraph>
    <Paragraph position="2"> wf-case-:frame g SENSE#:\[.</Paragraph>
    <Paragraph position="3"> wf-case-frame &amp; SERSE#2.</Paragraph>
    <Paragraph position="4"> wPS-case-frame g SENSE#n.</Paragraph>
    <Section position="1" start_page="854" end_page="855" type="sub_section">
      <SectionTitle>
3.1 Lexicon Entries
</SectionTitle>
      <Paragraph position="0"> Ea.ch verl) sense ('ntry in l;|le lexicon has the structure shown by the feature structm:e matrix in Fig- null The l:e~ture structure for erich synt~Lctic argument contains informal*ion about tim morphological and synthetic structure of the syntactic constituent such as p~trt-ofspeech, a.greemont, case, possessive markers, and additional morphological m;trkings such an verb form, (e.g., infinitive, partieiple, etc.), voice (e.g., active, passive, causatiw', reflexive, tee|proeM, etc.) for embed ded S's, ;done with their own case frames. This structure is simib~r to the structure proposed in Laser, rides cl al. (:1995). Ilowevcr, instead of classifying argument structures as simply tr~nsit, ive, intransitive, etc., we need to consider all relewmt elements of the l)ower set of t)ossible arguments. For Tm:kish, the syntactic constituents that we have chosen to in- null elude in the argument slot (for a verb in active voice) are the following: * subject (nominative NP), 1 * direct object (nominative or accusative ease-marked ~IP), * oblique objects (ablative, dative, locative case-marked NP), * beneficiary object (dative case-marked ~lP, or pP with a certain PFORN), * instrument object (instrumental case-marked gP or PP with a certain PFORIt), * value object (dative case-marked NP or PP with a certain PFORH).</Paragraph>
      <Paragraph position="1">  In general, there may be more than one instantiation of the SEM frame for a given instantiated set of case frame arguments (and vice versa). For instance, for the ye verb discussed above, the argument structure for the third case giving rise to the meaning to get mentally deranged may conceivably give rise to a literal meaning in a rather improbable context (such as eating the head of a fish at dinner - much in the spirit of the two interpretations of the English idiom kick the bucket), or the same semantics may be expressed by a different surface form.</Paragraph>
    </Section>
    <Section position="2" start_page="855" end_page="856" type="sub_section">
      <SectionTitle>
3.2 Constraint Arehlteeture
</SectionTitle>
      <Paragraph position="0"> We express constraints on the arguments in the case frame of a verb via a 5-tier constraint hierarchy sharing constraints among the specification of other constraints and sense definitions, whenever possible: NP's that have no case-marking in Turkish.</Paragraph>
      <Paragraph position="1">  1. Constraints on verb features that describe any relevant constraints on tile morphological features of the verb, such as agreement or voice markers.</Paragraph>
      <Paragraph position="2"> 2. Constraints on mou)hological features that describe any obligatory constraints on the arguments, such as case-marking, verb form (in the case of embedded clauses), etc.</Paragraph>
      <Paragraph position="3"> 3. Constraints on argument co-occurrence that express obligatory argument co-occurrence constraints along with constraints that indicate when certain arguments should not occur in order resolve a sense.</Paragraph>
      <Paragraph position="4"> 4. Lexieal constraints that indicate any specific constraints on the heads of the arguments in order to convey a certain sense, and usually constrain the stem of the head noun to be a certain lexical form, or one of a small set'of lexical forms.</Paragraph>
      <Paragraph position="5"> 5. Semantic Constraints that indicate seman null tic selectional restriction constraints that may resolved using a companion ontological database (again implemented in TFS) in which we model the world by defining semantic categories, such as human, thing, non-living object, living object, etc., along the lines described by Nagao et al. (1985).</Paragraph>
      <Paragraph position="6"> Figure 2 illustrates the simplified form of the constraint-sense mapping of the verb yc (eal). a.a Valeney Changing Transtbrmations As we have already stated, we encode senses of verbs in active voice unless a verb has an idiomatic usage with obligatory passive, causative and/or  rllles.</Paragraph>
      <Paragraph position="7"> This ligure describes how a given case fi'ame with its syntactic constituents is processed by a sequence of lexical rules each stripping off a certain voice marker and then attempting unification wii;h t;he lexicon for any possible sense resohttion. The order of lexieal rules in this figure reflects the reverse order of voice markers in 'Purkish verbal morphology, a So a given case frame m~y have to go through three lexical rules until it finds a unifying entry in the lexicon. \[h|itications before going through all lexical rule.s are for (possi-My idiomatic)senses which explicitly require w~rious voice \]na,rkings. Two additional constituents are a,dded via these lexieal rules. 'l'he AGI't-13B3 (agentive object), (\[enotes the equiwdent of the by-objecl in passiw', sentences. The sub.icct of the senl;ences a causative voice marked verb is indicated by CAUSER in the seInani;ics fi:ame. Our current implementation does not deal with multiple cansatiw: w)ice rnarkings (which Turkish allows), or with the rather tricky surface case change of the object of causation depending on the transitivity of Lit(: causativized verb. In the examples and sa.mple rules below, a voice marker can take one o\[' I;l||'ee wdues: (i) +: indicates the voice marker has to be l;aken. (ii) -: indica.tes the voice, marker is not |:M(en (iii) nil: indic~Ltes the voice mm:ker must not be taken; this is used only it, the sense detiuitions in the lexicon m|d cm~ unify with - but</Paragraph>
    </Section>
    <Section position="3" start_page="856" end_page="858" type="sub_section">
      <SectionTitle>
3.4 Examples
</SectionTitle>
      <Paragraph position="0"> In this section wc present n \[hw exmnples that show how one c~m describe a given verb sense.</Paragraph>
      <Paragraph position="1"> For the tirst example tile following constraints a.re employed: l. VERB-IS-YE is it constr~fint corresponding to \[vl.:itm I S't'r0:m: &amp;quot;ye'\]  2. VERB-TAKES-IqO-PASSIVE-NO-REFLEXIVE is the verb constr&amp;illt VEI{B: \[/I,'LX: nil 3. DIR-0BJ-ttAS-N0-POSS is the morphological eonstrainl, \[An C~s: I ~m~-OlIJ: Ivoss ....... \] 4. DIR-OBJ-IS-ACC is the morphological constraint |AlmS: I~)m-ouJ: I c:as~ ....... \] 5. NO-DATIVE-OBL-OBJ is the argument co occurrence constraint \[An.c;s: I,)AT-O|,L: ,,lit 6. SUBJEGT-IS-ttUMAig is the semantic constr~fint 7. DIR-OBJ-HEAD-LEX-KAFA is a lexical constraint |Alms: IDm-Ol3a: IIn.mD: ILItX: &amp;quot;k~t~&amp;quot;\] 8. SEM-GET-MEIgTt~LLY-DERANGED is the feature  structure for the semantics portion M| We can then express the constraint for the verb sense by unifying (denoted by g~ in 'FFS) all the  The resulting constraint when unified with partially specified case frarne entry -an entl:y where only tile argument and verb entries have been specified, will supply the unspecified SEN component(s). That is, when a partially specified ease \[rame such as  unifies successfully with the given constraint above, the unspecified portion will be properly instantiated with the experieneer being coindexed with the subject in the arguments.</Paragraph>
      <Paragraph position="2"> As a second example, consider tile default sense of ye corresponding to cat (somcthi~z.q). '\['he constraints are:  1. VERB-IS-YE is the verb constraint 2. VERB-TAKES-N0-REFLEXIVE is the verb c-onstraint \[vEa,: I I~\],'Lx: ,,ill 3. NO-DAT-OBL-OBJ is tile co-occurrence const,'ain~ \[AR.S: I--A'~-O\]~, .... i~\] 4. DIR-0Ba-IS(optional-ed+-ble) is the dis null junctive argument constraint (Tiffs is just explanatory, see below for how this is implemented in TFS.)  In inost eases, there are arguments that are not obligatorily required for resolving a verb sense. These, nevertheless, have to be constrained, usually on semantic grounds. For instance the direct object is not obligatory for the basic sense of ye, but has to be an edible entity if it, is present. We handle these constraints by defining a slightly more complex type hierarchy:</Paragraph>
      <Paragraph position="4"> where IS-A-EDIBLE is a constraint of the t'orrrt \[IIEAD: I SEM: edible\]. The optional ablative and instrumental objects are defined similarly. 4 The 4Note th~Lt the surface case constraints for these are defined in the ha,sic definition of the case fl:ame.</Paragraph>
      <Paragraph position="5">  sense definition then becomes:</Paragraph>
      <Paragraph position="7"> INST-OBJ-IS(optional-instrument) g SEN-EAT1.</Paragraph>
      <Paragraph position="8"> As a more cornplicated exaInl)le employing nested clauses, we presenl, below the case frame for the last example in Secl, ion 2, where the verb rut (catch) is used with a clausal subjecl; for a very specilic idiomatic usage.</Paragraph>
      <Paragraph position="9">  In this case, the sense resoluliou of the embedded case frame is also pe~Jbrmed concurrently with, the ease flame resolution of the lop-level frame.</Paragraph>
      <Paragraph position="10"> The last example below illustraLes the handling o\[' valency changing (;ransfortmttions where lexical I:ulcs hal~dle argument slmllling.</Paragraph>
      <Paragraph position="11"> (\]O CIl k a(\[al n \[,at af, n d an (Nild man by kar~,ya, geqirildi.</Paragraph>
      <Paragraph position="12"> oppo.sile_side pass+thUS +DAT +PRSS+PAST+3SG ('l'he~ child was passed to the opposil,e side I)y I, he mtm,) The Olltptl(; \['or this sentence is presenl;ed on the right.</Paragraph>
    </Section>
  </Section>
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