{ "paper_id": "C92-1035", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T12:33:13.952896Z" }, "title": "CATEGORIAL SEMANTICS FOR LFG", "authors": [ { "first": "Mary", "middle": [], "last": "Dalrymple", "suffix": "", "affiliation": { "laboratory": "", "institution": "Xerox PARC", "location": { "postCode": "94304", "settlement": "Palo Alto", "region": "CA", "country": "USA" } }, "email": "dalrymple@parc.xerox.com" } ], "year": "", "venue": null, "identifiers": {}, "abstract": "", "pdf_parse": { "paper_id": "C92-1035", "_pdf_hash": "", "abstract": [], "body_text": [ { "text": "A categorial semantics for Lexical-khmctional Grammar provides a means for semantic interpretation of sentences of natural language that is appropriately constrained both syntactically and semantically. The f-structure of LFG provides a cross-lingnistically uniform format for representing syntactic information; constraining a derivation with respect to the f-structure rather than a phrase structure tree allows reference to relevant functional syntactic information without requiring construction of a phrase structure tree whose form is (often dubiously) motivated on semantic grounds. Additionally, a categorial semantics constrains semantic derivations appropriately, obviating the need for an appeal to wellformedness conditions on the resulting semantic representation.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1" }, { "text": "Most semantic analyses appeal to syntactic constraints on semantic derivations. In particular, many analyses assume that such syntactic constraints are statable in terms of phrase structure tree configurations (Montague, 1974) . However, it is well-known that a variety of phrase structure configurations can express the same syntactic predicate-argunlent relations within and across languages (Kaplan and Bresnan, 1982) ; thus, syntactic constraints on semantic derivations are better expressed at a level at which the relevant syntactic information is expressed more uniformly. Such a level is the f-structure of LFG.", "cite_spans": [ { "start": 210, "end": 226, "text": "(Montague, 1974)", "ref_id": "BIBREF10" }, { "start": 394, "end": 420, "text": "(Kaplan and Bresnan, 1982)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Previous Work", "sec_num": "2" }, { "text": "Halvorsen (1983) first provided a theory of semantic interpretation for LFG in which semantic interpretation rules are related to the f-structure. His system involves an intermediate level of representation, the 'semantic structure', which is represented as a directed graph {like the f-structure). Translation rules map from f-structures to semantic structures, and these structures are then interpreted (or translated into a formula of intensional logic).", "cite_spans": [ { "start": 10, "end": 16, "text": "(1983)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Previous Work", "sec_num": "2" }, { "text": "The approach to be presented here also relies on f-structure configurations to provide syntactic constraints on categorial semantic derivations. However, an intermediate level of semantic representation such as Halvorsen's semantic structure is not introduced. In the categoriai semantic framework developed by Fernando Pereira (Pereira, 1990; Pereira and Pollack, 1991; , syntactic structures are directly associated with interpretations (or their types), and syntactic configurations license the combination of these interpretations in a semantic derivation. On this approach, 'logical forms' are not viewed as manipulable syntactic objects; instead, a logical formula is simply a graphical representation of a meaning that is lexically provided or that is the outcome of a semantically justified derivation. In this, the approach differs from other recent approaches to semantic interpretation in LFG (Halvorsen and , in which the interpretation of an fstructure is represented as a directed graph, and semantic derivation proceeds principally by unification of semantic representations. As a consequence, these approaches require constraints on semantic derivations to be stated as wellformedness conditions on semantic representations, contrary to the commonly-held goal of dispensabihty of logical form.", "cite_spans": [ { "start": 311, "end": 343, "text": "Fernando Pereira (Pereira, 1990;", "ref_id": "BIBREF12" }, { "start": 344, "end": 370, "text": "Pereira and Pollack, 1991;", "ref_id": "BIBREF11" } ], "ref_spans": [], "eq_spans": [], "section": "Previous Work", "sec_num": "2" }, { "text": "To illustrate a categorial semantic analysis within LFG, I will provide a small fragment of syntactic and semantic rules of English; the fragment contains rules for quantified noun phrases, nominal modification, and clauses headed by transitive and intransitive verbs. Many of these rules are modifications and extensions of rules originally described in Pereira (1990) , though Pereira's system appeals to phrase structure configurations rather than f-structures to con-strain semantic derivations; in particular, the rules Pereira provides for quantifiers and relative clauses have direct counterparts in the set of rules to be described below.", "cite_spans": [ { "start": 355, "end": 369, "text": "Pereira (1990)", "ref_id": "BIBREF12" } ], "ref_spans": [], "eq_spans": [], "section": "Previous Work", "sec_num": "2" }, { "text": "A sentence such as (1) has the interpretation given in (2): 1", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "(1) John crashed.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "( 2)crash (john) This interpretation is the outcome of a derivation according to a set of rules to be described below. Some of the rules must be licensed by particular f-structure configurations, while some are unrestricted in their apphcahihty. Example 1 has the following hstructure:", "cite_spans": [ { "start": 10, "end": 16, "text": "(john)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "(3) [PRED ,crash (SUBJ) , 1 [SkrBJ [PRED 'John']]", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "Annotated phrase structure rules hke the following are assumed: 2", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "S ---, NP VP (T suBJ)=~ 1- VP -~ V (NP) T=~ (T oB~)=l", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "Notice that these phrase structure rules encode only syntactic information. No semantic information or constraints are required. The lexical entries involved in the derivation of sentence (1) are:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "John NP (I PRED)= 'John' I~ = [OP/] crashed V (T PILED)= 'crash(suBJ}' (, TENSE) = PAST (T PRED)a : [O [-Ax.crash(z)]", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "The notation f~, stands for the interpretation of an f-structure f, often referred to as the semantic projection of f (Kaplan, 1987; Halvorsen and Kaplan, 1988) . The interpretation for any f-structure f is a sequent:", "cite_spans": [ { "start": 118, "end": 132, "text": "(Kaplan, 1987;", "ref_id": "BIBREF9" }, { "start": 133, "end": 160, "text": "Halvorsen and Kaplan, 1988)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "1I will ignore tense and aspect in the representation of sentence meanings.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "2See Bresnan (1982) for an explication of the relation between c-structure and f-structure and the notation commonly used to represent that relation.", "cite_spans": [ { "start": 5, "end": 19, "text": "Bresnan (1982)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Sentence Interpretation", "sec_num": "3" }, { "text": "The sequent '[a ~ M]' is a pair consisting of a set of assumptions a, somewhat analogous to a 'quantifier store ' (Cooper, 1983) , and a matrix term M in which free variables introduced by the asstutlptions in a may occur (Pereira, 1990; Dalrymple et al., 1991) . In the following, I will speak of such expressions as introducing the meaning M under the assumptions in a.", "cite_spans": [ { "start": 112, "end": 128, "text": "' (Cooper, 1983)", "ref_id": null }, { "start": 222, "end": 237, "text": "(Pereira, 1990;", "ref_id": "BIBREF12" }, { "start": 238, "end": 261, "text": "Dalrymple et al., 1991)", "ref_id": "BIBREF3" } ], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "I assume a fixed order of application of the meaning of a verb to its semantic arguments, with the order determined by the syntax (though this assmnption is not crucial to the analysis). Arguments are applied in the following order: s", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "(1) Obliques", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "(2) o,~2", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "(3) osJ (4) sunJ", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "The PILED of the f-structure of an active verb such as own will, then, be associated via the a mapping with the following interpretation:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "Ay. Ax.own(x,y) Notice that the verb is required to combine with the object first, and then the subject, in accordance with the argument ordering given above. ]:'or a passive verb, the ordering will be reversed.", "cite_spans": [ { "start": 4, "end": 15, "text": "Ax.own(x,y)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "For the passive verb (be) owned, the order will be:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "(6) x~.~v.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "(4) G:[o~-M]", "sec_num": null }, { "text": "Here, the verb combines first with the oblique by-phrase, then with the subject. The rule for interpreting art f-structure for a clause headed by an intransitive verb is: 4 7Clause with intransitive verb:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "3This order of application was also proposed by Dowry (1982) , and is reminiscent of the obliqueness ordering for arguments in HPSG (Pollard and Sag, 1987) .", "cite_spans": [ { "start": 48, "end": 60, "text": "Dowry (1982)", "ref_id": null }, { "start": 132, "end": 155, "text": "(Pollard and Sag, 1987)", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "4This rule should apply when f has a PRED and a sUB J, but no other governable grammatical functions; it should not apply if the verb is transitive and there is a slJl~J and an oB3, although f is unifiable with tile f-structure of a transitive verb as well as an intransitive one. There are several ways of ensuring the needed result: the valence of tire verb can be reflected in its semantic type; f-structures can be typed, with this rule applying only to intransitive f-structures (Zajac and Emele, 1990) ; or the PROD and its arguments can be separately specified, with the argumarts of the PRED specified as a list which can be mntched The derivation of the meaning f~ of an fstructure f with a PRED and SUBJ proceeds by applying the meaning of the PILED to the meaning of the suBJ. The associated assumption set is the union of the assmnptions from the PRED and the SUna. The f-structure for sentence 1 hcenses the following derivation and provides the expected meaning (under a null assumption set):", "cite_spans": [ { "start": 484, "end": 507, "text": "(Zajac and Emele, 1990)", "ref_id": "BIBREF16" } ], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "(8) ['p RED f2:,craah (SUBJ) , J ks.., 'John']]", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "Lexically specified meanings:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "(f~)~ = [0 ~-Ax.crash (~}] (fa),~ --[0 ~-j]", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "By rule 7:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "(fl)~ = [0 U 0 l-Ax.erash(x)(j)] = [0 }-crash(j)] 4 Quantification", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "Sentence 9 contains a quantified noun phrase and has the meaning represented in (10):", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "(9) Every car crashed.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "(10) every(Ay.car(y), Az.craMz(x))", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "This sentence has the f-structure shown in (11), constructed on the basis of the lexical entries below:", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "ow,t(~,v)", "sec_num": null }, { "text": "(11) [Pa~D 'c~ash