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<Paper uid="C94-1057">
  <Title>The Correct Place of Lexical Semantics in Interlingual MT</Title>
  <Section position="2" start_page="0" end_page="349" type="abstr">
    <SectionTitle>
2. The model
</SectionTitle>
    <Paragraph position="0"> Traditionally, intcrlingual MT systems which employ a full-Iflown syntactic module (e.g., KBMT-g9 (Goodman * ~tnd Nircifl)mg, 1992) or KANT (Carl~onell et al., 1992)) use a single mapping between syntactic structure and inlerlingua. In Mikrokosmos, we propose a different model, as illustrated in Figure 1. Lexical-cotlcel~lual SlrUCtures (LCSs) have been suggested its meaning represenlalions for n,'ilural language sentences produced in accordance with the semantic theory developed by I lale and Jaekendo11&amp;quot; (e.g., Jackendoff, 1983) and used in MT-related experimenls by Dorr (l)orr, 1993). The inlerlingtmtext (or texl meaning representation, TMR) is a slructt~re which represents meaning of texts in accor(laL~ce with Ihe ontologyoriented ;.ipl)roach to COml)tllational seitlantit:s (see Ni,cnburg and Lcvin, 1992).</Paragraph>
    <Paragraph position="1"> It is convenient 1() sh-LlCttlre oLlr ,argtHlicLlt for Otis mo(lel arotmd the tmcstions below (refcrrine to labels in Figure 1), which we will discuss one-hy-onc in lhe following  I. llow similm are structures I and 3? flow are they different? 2. lie)v+, similar are mappings A and D'? Ih),,v are they (lill'crenf.~ 3. lh)w is slrtlctlne 2 diffcrenl from slrilCltlres l and 3'? 4. WILy are rel)tesentalions l, 2, .~llld 3 all lleCessary?</Paragraph>
    <Section position="1" start_page="0" end_page="349" type="sub_section">
      <SectionTitle>
2.1. Are LexicaI-Coneeplual Structures
</SectionTitle>
      <Paragraph position="0"> I,:mguage-Universal? Attempts have been made to use I+CSs as interlitlgtias for M'I' (notably, Dorr, 1993). The impetus Ibr such work is provided by obserwttions that in mlmy cases LCSs for translation equivalents are, in fact, identical. The many cases in which LCSs are not identical across lan+ gtmI,es pose prol)lems for this apprt)ach. Methodologically, therefore, tile type o1' work in LCg-as-itlterlingua projects is tinding ways of resolving e'ich such cane, based on observing cross-linguistic divergences in realizing meanings. There is a danger Ihat some of the divergences will prove unlreatable at the LCS level and, alternatively, that solulions for some problems will necessilale changes I() tile naltH'e of the L'epreseEIlalion which will make the resulting struclurc resemble tile original LCS in progressively smaller ways. The problematic cases will be those in which translation equivalenls can  have differerit lexical sem,'mtics. We will inention two snch cases here.</Paragraph>
      <Paragraph position="1"> The first problem arises in the context of a complex event, such as a merger of two companies, which can lie described by mentioning ,'my of its llarts (bids, tiegotiations, etc.). This is particularly problematic when different langnages, by convention or for ease of expression, refer to dill'ereut parts of the complex event. In fact, snch divergences exist even within one language. For example, you c:m go to a lneeting (directed motion), attend a meeting (activity), or be at a lneeting (state). Similarly, while in English one takes a taxi, using a mmsitive verb, the cor,esponding Japmlese for the stone event it takusi ni noru (get on, board, ride in a taxi), using an intrmlsitive verb with a gem argument. Even seemingly atomic events and states can be broken down into their :tspectual components to consist of events leading np to changes of slate that result in new slates. For exgmlple, lhe siluation of knowing something can be expressed in English using the stative verb know or in Japanese using a nonstalive verb siru (come to know) in its restlltative Ibznl site iru (Lit: have coine to know). In examples snch as these, there will be no direct correspondence at the level of lexical semantics in individual lmlguages.</Paragraph>
      <Paragraph position="2"> The second circumstance in which translation eqnivalents have different lexical selmmtics is that an element of metaling tllat is expressed as :m m'gnment-taking predicale in one l~mguage might not be expressed as an argument-taking predicate in ~mother langnage. Well-knowu examples from MT literature include like vs. germ verlir de vs. just, etc. However, lhis phenomenon is much more widespread than normally acknowledged in the MT literature. Things that are expressed as ln:dn or auxiliary verbs in English, but are not verbs at all in Japanese inchlde m~my high-frequency meaning elements sucli as phase (begin, continue, finish), modality (mt4stlshottld, plan, expect, try), mid evidentiality (seem, appeal; look like). In fact, thesyntactic means for encoding these types of megming vary wildly among lmlguages, going far beyond the well-known verb-adverb divergences. This is why ill the Mikrokosmos intcrlingua we represent snch elements of meaning as features or operators that scope over clauses mid propositions.</Paragraph>
      <Paragraph position="3"> 2.2. Ilow is an lnterlingua Different from an SI)LS Oittput? In the cases described above in which a sitlgle event is described witll different lexical sem~mtics the meaning shared by each member in the set of paraphrases makes a better c,'mdidale for the interlingu~d semautic representation thml does the lexic~d semantics; and it is lhis type of meaning that we are striving to extract ,'rod represent ill the interlingna text in Mikrokosmos. Additionally, while SDLS concentrales on the &amp;quot;who-did-what-to-whom&amp;quot; aspect of text meaning, TMRs cont~dn additional meaning facets, such as ,'tspect, modality, evidentiality, speech acl, reference, etc. Finally, as TMRs ~u'e not based on lhe lexic:d semantics of one particular lmlguage, there is no special benetit to be accrued from the imposition of the requirement to preserve predicate-~u'gument stnlctures.</Paragraph>
      <Paragraph position="4"> 2.3. Universals of Semantic Role Assignment It is very enticing to be able to apply principles of lexical mapping theory cross-lingnistic:dly. Similarities that have been observed across languages inv01ve linkings of semantic rotes to syntactic positions or gramnialical fnnclions, transitivity alternations,and verb el:roses. The latter have been described if+ solnC/ detail for English by B. Levin (1C/)93) ~md others. Thns, to ltte extent flu+l the hypothesis of cross-linguistic equivalence holds, the descriptioli of similar phenomena in other l+mguages, for the pnrposes of M'I, becomes much simpler, it not ntterly trivial.</Paragraph>
      <Paragraph position="5"> l lowever, langnages, as :t rn\[e, have different transitivity altern'ltions (Mitamura 1999) and even when they have a similar transitivity alternalion, the classes of verbs to which they ;tpply may be different. See Mahmoud 1999 for a discussion of the differences in the verbs Ih:lt nndergo the cansative-inchoative altern:ttion in English and Arabic) It is, of course, desirable to take advantage of universals, bill it is also necessary to have a syslem that is tlexible enongh to accommodate cross-linguistic V,+lriation.</Paragraph>
      <Paragraph position="6"> 7.4. hliegl+allon of SI)I+S into hilerlingilal MT Taking a l)osition on the necessity of both SDLS and TMR has to be based on a general approach 1o nnraveling the form-nleaning correspondence. For example, to make a TMR for John began to read we need to identify a nnmbcr of meaning elements, prilnarily Ihat something look place hefore the time of speech, which was the beginning plut,;e of a re&lt;iding evenl carried ont by John. 2 I low do we lind tllese pieces of information? Tinle before the time of speecll is indicated by the mos7Jfiolog j of&amp;quot;began&amp;quot;. The beginning phase is typically intlicnled h, xically by the verb begin in English. We know that it is the beginning phase of reading becanse the syntax module tells us thai to reed is the complement of begin. We know Ihat John is reading because John is the snbject of begin (once again, the sytllaelic module produced this element of informalion), whose lexical properties tell us thai John is also nnderstood as the subject of the complcment clause. In oilier words, it is the predicate argnnienl structure of begin (prodnced by the synlax-to-S DLS mapping procedure ill the lexicon entry for begin) Ihat tells ils where to lind ulany of the relevant pieces of information.</Paragraph>
      <Paragraph position="7"> l laving lhns served the purpose of identifying a part of the selnanlic dependency Io be represeuled in tile linal TMR (just as the liudings of other syslenl modtnles played their assigned roles as clnes for delermining paris of Ihe TMR strnctnre), Ihe predicate :u'gulnent slnctnre can then be disc:tided. In Ihe l%~llowing seclion we give sonic delailed exanlplcs of Ihe nlappings involved in prodncing SDLS OUllnll strnctures and TMl,ts :ts well :is relevant paris of lexicon erllries.</Paragraph>
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