{ "paper_id": "W98-0129", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T06:06:04.650629Z" }, "title": "Description Theory, LTAGs and Underspecified Semantics*", "authors": [ { "first": "Reinhard", "middle": [], "last": "Muskens", "suffix": "", "affiliation": { "laboratory": "", "institution": "Tilburg University", "location": { "postBox": "P.O. Box 90153", "postCode": "5000 LE", "settlement": "Tilburg", "country": "The Netherlands" } }, "email": "" } ], "year": "", "venue": null, "identifiers": {}, "abstract": "", "pdf_parse": { "paper_id": "W98-0129", "_pdf_hash": "", "abstract": [], "body_text": [ { "text": "An attractive way to model the relation between an underspecified syntactic representation and its completions is to let the underspecified representation correspond to a logical description and the completions to the models of that description. This approach, which underlies the Description Theory of (Marcus et al. 1983) has been integrated in (Vijay-Shanker 1992} with a pure unification approach to Lexicalized Tree-Adjoining Grammars (Joshi et al. 1975 , Schabes 1990 . We generalize Description Theory by integrating semantic information, that is, we propose to tackle both syntactic and semantic underspecification using descriptions. 1 Our focus will be on underspecification of scope. We use a generalized version of LTAG, to which we shall refer as LFTAG. Although trees in LFTAG have surface strings at their leaves and are in fact very close to ordinary surface trees, there is also a strong connection with the Logical Forms (LFs) of (May 1977) . We associate logical interpretations with these LFs using a technique of intemalising the logical binding mechanism (Muskens 1996) . The net result is that we obtain a Description Theory-like grammar in which the descriptions underspecify semantics. Since everything is framed in classical logic it is easily possible to reason with these descriptions.", "cite_spans": [ { "start": 303, "end": 323, "text": "(Marcus et al. 1983)", "ref_id": "BIBREF5" }, { "start": 440, "end": 458, "text": "(Joshi et al. 1975", "ref_id": "BIBREF3" }, { "start": 459, "end": 473, "text": ", Schabes 1990", "ref_id": "BIBREF10" }, { "start": 948, "end": 958, "text": "(May 1977)", "ref_id": "BIBREF6" }, { "start": 1077, "end": 1091, "text": "(Muskens 1996)", "ref_id": "BIBREF8" } ], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null }, { "text": "Descriptions in our theory model three kinds of information. First, there are input descriptions, which", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "\u2022we wish to thank Kurt Eberle, Barbara Partee, Stanley Peters and all other participants of the Bad Teinach Workshop on Models of Underspecification and the Representation of Meaning (May 1998) for their comments and criticisms on an earlier version of this paper.", "cite_spans": [ { "start": 183, "end": 193, "text": "(May 1998)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "1 The approach to underspecified semantics taken in (Muskens 1995) was very much inspired by Description Theory and the work ofVijay-Shanker in (Vijay-Shanker 1992) but did not offer an actual integration with Tree-Adjoining Grammars. In this paper we endeavour to set this right.", "cite_spans": [ { "start": 52, "end": 66, "text": "(Muskens 1995)", "ref_id": "BIBREF7" } ], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "Emiel Krahmer IPO Eindhoven University of Technology P.O. Box 513 5600 lvIB Eindhoven, The Netherlands krahrner\u00a9ipo.tue.nl vary per sentence. For example, for sentence (1) we have (2) as an input description. lt says that there are two lexical nodes, 2 labeled John and walks respectively; that the first of these precedes the second; and that these two lexical nodes are all that were encountered. Secondly, there is a lexicon which includes semantic information. The ent ries for John and walks are given in (3) and (4).", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "(1) John walks.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "( ", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "EQUATION", "cite_spans": [], "ref_spans": [], "eq_spans": [ { "start": 0, "end": 8, "text": "EQUATION", "ref_id": "EQREF", "raw_str": "2) 3n1n2(lex(n1)i\\lex(n2)J\\n1-< n2i\\lab{n1,john)J\\ lab(n2, waiks) A Vn(lex(n) -t (n = n1 V n = n2))) (3) \\ln 1 (lab(n1,john) -t 3n3(/ab(n3,11p)i\\n3 .v.wa/k v))", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "The function symbol a+ used in these descriptions positively anchors nodes to lexical nodes, a-negatively anchors nodes and q gives a node its semantic value. ", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "/'---.... det4 11!1 ~ ~ det11 n!2 nfi Vu np1a nj9 1 1 1 1 1 every5 man20 loves12 '118", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "womann Figure 1 : Elementary descriptions for every man loves a woman negative anchoring in the following way. lf a description contains the information that a certain nonlexical node is positively (negatively) anchored, the term referring to that node gets a plus (minus) sign. But pluses and minuses cancel and terms that would get a \u00b1 by the previous rule will be left unmarked. Terms marked with a plus (minus) sign are to be compared with the bottorn (top) parts of Vijay-Shanker's 'quasi-nodes' in (Vijay-Shankar 1992). There is also an obvious close connection with positive (negative) occurrences of types in complex types in Categorial Grammar.", "cite_spans": [], "ref_spans": [ { "start": 7, "end": 15, "text": "Figure 1", "ref_id": null } ], "eq_spans": [], "section": "Syntactic Composition", "sec_num": "1" }, { "text": "To the third and final kind of descriptions belang\u2022 a.\"' u(n2)) u(n10) = >.v.v loves u(n13) u(n1) = u(n9 )(u(ns)) a(n 16 ) = Unu u(n14) = some Un 18 [a(n19)(un 18 ) ", "cite_spans": [ { "start": 151, "end": 165, "text": "(Muskens 1996)", "ref_id": "BIBREF8" }, { "start": 248, "end": 267, "text": "(Kamp & Reyle 1993)", "ref_id": "BIBREF4" }, { "start": 408, "end": 411, "text": "\u2022 5", "ref_id": null }, { "start": 752, "end": 770, "text": ">.v.v loves u(n13)", "ref_id": null }, { "start": 828, "end": 843, "text": "[a(n19)(un 18 )", "ref_id": null } ], "ref_spans": [ { "start": 681, "end": 687, "text": "fig. 1", "ref_id": null } ], "eq_spans": [], "section": "Internalising Binding", "sec_num": "2" }, { "text": "& a(n15)] u(n2il = >.v.man v u(n22) = >.v.woman v", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Internalising Binding", "sec_num": "2" }, { "text": "The first two equations derive from the lexical item for every, the third and fourth from loves, the fifth and sixth from a, and the last two from the common nouns. Note that in the translation of every, n 3 only gets a referent as its translation (namely u(n 5 ), which for readability we write as tln 5 ), while the real action is taking place upstairs. A similar remark holds for the other determiner.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Internalising Binding", "sec_num": "2" }, { "text": "As we have seen earlier, in any model of the relevant descriptions ns = n21, nrn = n22, n 9 = n 10 , Note that this is the point where we have made essential use of our internaHsation of binding: had we used ordinary variables instead of our registerdenoting terms, the substitution would not have been possible. Continuing our reasoning, we see that \u00b5nder the given assumption the root node r (=n 14 in this 115 case) will be assigned the 3V reading of the sentence. Without assumptions the disjunction in fig. 2 is derivable.", "cite_spans": [], "ref_spans": [ { "start": 507, "end": 514, "text": "fig. 2", "ref_id": null } ], "eq_spans": [], "section": "Internalising Binding", "sec_num": "2" }, { "text": "na =", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Internalising Binding", "sec_num": "2" }, { "text": "We conclude that the leading idea behind Marcus' Description Theory allows us to underspecify semantic information much in the same way as syntactic information is underspecified in this theory. The price is that we must accept that different semantic readings correspond to different structures, as the method only allows underspecification of the latter.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Internalising Binding", "sec_num": "2" }, { "text": "With lexical nodes we mean those leaves in a tree which carry a lexeme.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null }, { "text": "In this paper only quantification into S is considered but in a fuller version we shall generalise this to qua~tification into arbitrary phrasal categories.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "", "sec_num": null } ], "back_matter": [], "bib_entries": { "BIBREF0": { "ref_id": "b0", "title": "A First-Order Axiomatization of the Theory of Finite Trees", "authors": [ { "first": "R", "middle": [], "last": "Backofen", "suffix": "" }, { "first": "J", "middle": [], "last": "Rogers", "suffix": "" }, { "first": "K", "middle": [], "last": "Vijay-Shanker", "suffix": "" } ], "year": 1995, "venue": "Journal of Logic, Language and Information", "volume": "4", "issue": "", "pages": "5--39", "other_ids": {}, "num": null, "urls": [], "raw_text": "Backofen, R., J. Rogers and K. Vijay-Shanker. 1995. A First-Order Axiomatization of the Theory of Fi- nite Trees. Journal of Logic, Language and Infor- mation 4:5-39.", "links": null }, "BIBREF1": { "ref_id": "b1", "title": "Quantification and Syntactic Theory", "authors": [ { "first": "R", "middle": [], "last": "Cooper", "suffix": "" } ], "year": 1983, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Cooper, R. 1983. Quantification and Syntactic The- ory. Reidel. Dordrecht.", "links": null }, "BIBREF2": { "ref_id": "b2", "title": "On Determining the Consistency of Partial Descriptions of Trees", "authors": [ { "first": "T", "middle": [], "last": "Cornell", "suffix": "" } ], "year": 1994, "venue": "Proceedings of ACL 94", "volume": "", "issue": "", "pages": "163--170", "other_ids": {}, "num": null, "urls": [], "raw_text": "Cornell, T. 1994. On Determining the Consistency of Partial Descriptions of Trees. Proceedings of ACL 94. 163-170.", "links": null }, "BIBREF3": { "ref_id": "b3", "title": "Tree Adjunct Grammars", "authors": [ { "first": "A", "middle": [], "last": "Joshi", "suffix": "" }, { "first": "L", "middle": [], "last": "Levy", "suffix": "" }, { "first": "M", "middle": [], "last": "Takahashi", "suffix": "" } ], "year": 1975, "venue": "Journal of the Computer and System Sciences", "volume": "10", "issue": "", "pages": "136--163", "other_ids": {}, "num": null, "urls": [], "raw_text": "Joshi, A., L. Levy and M. Takahashi. 1975. Tree Adjunct Grammars. Journal of the Computer and System Sciences 10: 136-163.", "links": null }, "BIBREF4": { "ref_id": "b4", "title": "From Discourse to Logic", "authors": [ { "first": "H", "middle": [], "last": "Kamp", "suffix": "" }, { "first": "U", "middle": [], "last": "Reyle", "suffix": "" } ], "year": 1993, "venue": "", "volume": "", "issue": "", "pages": "", "other_ids": {}, "num": null, "urls": [], "raw_text": "Kamp H. and U. Reyle. 1993. From Discourse to Logic. I", "text": "that .A9 and .AlO in themselves do not suffice to exclude that some nodes are connected by a dominance relation without there bcing a (finite) path of immediate dominances between them. In fact the nature or our input descriptions and the form of our lexicon exclude this.", "num": null, "type_str": "table" }, "TABREF3": { "html": null, "content": "
Figure 2: A Derivable Disjunction
3 Semantic Composition
\\Ve can now integrate semantic equations with the
lexical items occurring in
", "text": "u(r) = all Un 5 (man Un 5 => sorne ~n 18 [woman Unis & Uns loves Un 18 ]JV u(r) = sorne Un 18 [ woman Un 1 s & all Uns [man Un 5 => Uns loves Un 1 sJJ", "num": null, "type_str": "table" }, "TABREF4": { "html": null, "content": "
a(n1) = Uns loves Un 1 s
u(n1) = alluns[manun 5 =>cr(n2))
<7(n14)= some Un 1 s [ woman tln 18 & cr(n1s)}
", "text": "n3, and n13 = nl6 hold. From this it follows that The relevant constraints further imply that either nz = n14 and n1s = n1, or, alternatively, that n 15 = n1 and n2 = n7. For the moment Jet us assurne the second possibility. Since Uns loves Un 18 is a c/osed term (u is a function constant and ns and n 18 are constants that witness existential quantifiers in the input description of (5)), the assumption that n2 = n 7 allows us to conclude that cr(ni) = all Un 5 [man Uns => Un 5 loves tln 18 ]", "num": null, "type_str": "table" } } } }