Linking Syntactic and Semantic Arguments in a Dependency-based Formalism

Linking syntactic and semantic arguments in a dependency-based formalism Christian Korthals and Ralph Debusmann Computational Linguistics Universit¨at des Saarlandes, Geb. 17 Postfach 15 11 50 66041 Saarb¨ucken, Germany (cnkortha|rade)@coli.uni-sb.de Abstract We propose a formal characterization of variation in the syntactic realization of semantic arguments, using hierarchies of syntactic relations and thematic roles, and a mechanism of lexical inheritance to ob- tain valency frames from individual linking types. We embed the formalization in the new lexicalized, dependency-based grammar formalism of Topologi- cal Dependency Grammar (TDG) (Duchier and De- busmann, 2001). We account for arguments that can be alternatively realized as a NP or a PP, and model thematic role alternations. We also treat auxiliary constructions, where the correspondance between syntactic and semantic argumenthood is indirect.1 1 Introduction This paper deals with the mapping (or linking) of se- mantic predicate-argument structure to surface syn- tactic realizations. We present a formal architecture in the framework of a multi-dimensional, heavily lexicalized, efficiently parsable dependency formal- ism (Duchier and Debusmann, 2001), which uses lexical inheritance as a means to explicitly model syntactic variation. We concentrate on variation be- tween prepositional phrases and nominal phrases which realize verbal arguments, and remedy prob- lems that occur with this kind of variation in recent approaches like the HPSG linking architecture pro- posed by (Davis, 1998). Section 2 presents and analyses some of the prob- lematic data we can model, English dative shift, op- tional complements and thematic role alternations. Section 3 compares the HPSG account with less for- mal valency or dependency based approaches and comments on the shortcomings, focusing on the treatment of PP complements. We then present a new account in the formal framework of Topologi- 1The authors wish to thank Denys Duchier and Geert-Jan Kruijff for lots of helpful comments on this paper. cal Dependency Grammar (TDG) by adding a new representational level (thematic structure addition- ally to ID structure) to the framework in Section 4.1 and introducing the concept of a valency frame in the TDG inheritance lexicon (Sections 4.2 and 4.3). We then show how we use syntactic role hi- erarchies to account for the data in a linguistically concise way and define admissibility conditions for a TDG derivation. Section 5 contrasts our analysis of the dative shift construction with the analysis of thematic role alternations. 2 Linguistic Data Insights from corpus studies (e.g. the NEGRA treebank for German (Skut et al., 1998), or the material annotated in the Framenet (Baker et al., 1998) project on the basis of The Bank of English (Cobuild, 2001) show that the syntactic patterns specific verbs occur with vary stongly. Not only do we observe different patterns for different verbs, but also alternative patterns with the same verbs. (1) to (6) illustrate the well-known dative shift (Levin, 1993):45 phenomenon, which occurs with a re- stricted class of verbs only. While the distinction between (2) and (4) can be explained in terms of lexical semantics, even semantically closely related verbs as English give and deliver can differ in …

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