Generating Parallel Multilingual LFG-TAG Grammars from a MetaGrammar

Generating parallel multilingual LFG-TAG grammars from a MetaGrammar Lionel Cl´ement Inria-Roquencourt France lionel.clement@inria.fr Alexandra Kinyon CIS Dpt - Univ. of Pennsylvania kinyon@linc.cis.upenn.edu Abstract We introduce a MetaGrammar, which al- lows us to automatically generate, from a single and compact MetaGrammar hier- archy, parallel Lexical Functional Gram- mars (LFG) and Tree-Adjoining Gram- mars (TAG) for French and for English: the grammar writer specifies in compact manner syntactic properties that are po- tentially framework-, and to some extent language-independent (such as subcatego- rization, valency alternations and realiza- tion of syntactic functions), from which grammars for several frameworks and languages are automatically generated offline.1 1 Introduction Expensive dedicated tools and resources (e.g. gram- mars, parsers, lexicons, etc.) have been developed for a variety of grammar formalisms, which all have the same goal: model the syntactic properties of nat- ural language, but resort to a different machinery to achieve that goal. However, there are some core syn- tactic phenomena on which a cross-framework (and to some extent a cross-language) consensus exists, such as the notions of subcategorization, valency al- ternations, syntactic function. From a theoretical perspective, a MetaGrammatical level of representa- tion allows one to encode such consensual pieces of syntactic knowledge and to compare different frame- works and languages. From a practical perspective, encoding syntactic phenomena at a metagrammati- cal level, from which grammars for different frame- works and languages are generated offline, has sev- eral advantages such as portability among grammat- ical frameworks, better parallelism, increased coher- ence and consistency in the grammars generated and less need for human intervention in the grammar de- velopment process. In section 2, we explain the notion of MetaGram- mar (MG), present the MG tool we use to gener- ate TAGs, and how we extend the approach to gen- erate LFGs. In section 3, we justify the use of a MetaGrammar for generating LFGs and explore sev- eral options, i.e. domains of locality, for doing so. In sections 4 and 5, we discus the handling of va- lency alternations without resorting to LFG lexical 1We assume the reader has a basic knowledge of TAGs and LFGs and refer respectively to (Joshi, 1987) and (Bresnan and Kaplan, 1982) for an introduction to these frameworks. rules, and the treatment of long-distance dependen- cies. In sections 6 and 7, we discuss the advantages of a MG approach and the automatic generation of par- allel TAG-LFG grammars for English and for French with an explicit sharing of both cross-language and 2cross-framework syntactic knowledge in the MG. What is a MetaGrammar ? The notion of MetaGrammar was originally pre- sented in (Candito, 1996) to automatically generate wide-coverage TAGs for French and Italian2, using a compact higher-level layer of linguistic description which imposes a general organization for syntactic information in a three-dimensional hierarchy: • Dimension 1: initial subcategorization • Dimension 2: valency alternations and redistri- bution of functions • Dimension 3: surface realization of arguments. Each terminal class in dimension 1 encodes an initial subcategorization (i.e. transitive, ditransitive etc...); Each terminal class …

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