Porting Grammars between Typologically Similar Languages : Japanese to Korean

Porting Grammars between Typologically Similar Languages: Japanese to Korean Roger KIM Palo Alto Research Center 3333 Coyote Hill Rd. Palo Alto, CA 94304 USA rkim@parc.com Ronald M. KAPLAN Palo Alto Research Center 3333 Coyote Hill Rd. Palo Alto, CA 94304 USA kaplan@parc.com Mary DALRYMPLE Dept. of Computer Science King's College London Strand, London WC2R 2LS UK mary@dcs.kaac.uk Tracy Holloway KING Palo Alto Research Center 3333 Coyote Hill Rd. Palo Alto, CA 94304 USA thking@parc.com Abstract We report on a preliminary investigation of the difficulty of converting a grammar of one lan- guage into a grammar of a typologically similar language. In this investigation, we started with the ParGram grammar of Japanese and used that as the basis for a grammar of Korean. The re- sults are encouraging for the use of grammar porting to bootstrap new grammar development. 1 Introduction The Parallel Grammar project (ParGram) is an international collaboration aimed at producing broad-cov- erage computational grammars for a variety of languages (Butt et al., 1999; Butt et al., 2002). The gram- mars (currently of English, French, German, Japanese, Norwegian, and Urdu) are written in the frame- work of Lexical Functional Grammar (LFG) (Kaplan and Bresnan, 1982; Dalrymple, 2001), and they are constructed using a common engineering and high-speed processing platform for LFG grammars, the XLE (Maxwell and Kaplan, 1993). These grammars, as do all LFG grammars, assign two levels of syntac- tic representation to the sentences of a language: a superficial phrase structure tree (called a constituent structure or c-structure) and an underlying matrix of features and values (the functional structure or f- structure). The c-structure records the order of words in a sentence and their hierarchical grouping into phrases. The f-structure encodes the grammatical functions, syntactic features, and predicate-argument relations conveyed by the sentence. F-structures are meant to encode a language universal level of anal- ysis, allowing for cross-linguistic parallelism at this level of abstraction. The ParGram project attempts to test the LFG formalism for its universality and coverage and to see how far parallelism can be maintained across languages. Previous ParGram work and much theoretical analysis has largely confirmed the universality claims of LFG theory. The f-structures produced by the grammars for similar constructions in each language have the same major functions and features, with minor variations across languages (e.g., the f-structures for French nouns have a grammatical gender fea- ture but that distinction is not marked in English f-structures). This uniformity has the computational ad- vantage that the grammars can be used in similar applications and that machine translation (Frank, 1999) can be simplified. We have found that it takes roughly two person-years of effort to construct for a new language a gram- mar that approximates existing grammars in terms of coverage and accuracy (see (Riezler et al., 2002) for a discussion of the coverage and accuracy of the current English grammar). This suggests that the deep-grammar construction task is not as difficult as many people have believed, and indeed may require less effort than would be …

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