Lean Formalisms, Linguistic Theory and Applications. Grammar Development in ALEP.

Lean Formalisms~ Linguistic Theory~ and Applications. Grammar Development in ALEP. Paul Schmidt & Axel Theofilidis & Sibylle Rieder IAI Martin-Luther-Str. 14 D-66 111 Saarbrficken {paul,axel,sibylle} @iai.uni-sb.de Abstract This paper describes results achieved in a project which addresses the issue of how the gap between unification-based grammars as a scientific concept and real world applications can be narrowed down 1. Application-oriented grammar development has to take into ac- count the following parameters: Efficiency: The project chose a so called 'lean' formal ism, a term-encodable language providing effi- cient term unification, ALEP. Coverage: The project adopted a corpus-based approach. Completeness: All modules needed from text handling to semantics must be there. The paper reports on a text handling compo- nent, Two Level morphology, word structure, phrase structure, semantics and the interfaces between these components. Mainstream ap- proach: The approach claims to be main- stream, very much indebted to HPSG, thus based on the currently most prominent and recent linguistic theory. The relation (and tension) between these parameters are de- scribed in this paper. 1 Introduction Applications on the basis of unification-based gram- mars (UG) so far are rather rare to say the least. Though the advantages of UGs are obvious in that properties such as monotonicity, declarativity, per- spicouity are important for maintaining and easily extending grammars, their popularity (despite 15 years of history) is still restricted to the academia. This paper reports of a project, LS-GRAM, which tried to make a step further in bringing UGs closer to applications. Application-oriented grammar development has to take into account the following parameters: • Efficiency: A major problem of UGs is (lack- ing) efficiency. For the LS-GRAM project this 1This project is LS-GRAM, sponsored by the Com- mission of the European Union under LRE 61029. Thierry Declerek IMS, University of Stuttgart Azenbergstr. 12 D-70174 Stuttgart thierry@ims.uni-stuttgart.de led to the decision to use a so called 'lean' for- nrMism, ALEP, providing efficient term unifi- cation. 'Leanness' means that computation- ally expensive formal constructs are sacrificed to gain efficiency. Though this is at the cost of expressiveness, it is claimed that by 'leanness' 'hnguistic felicity' does not suffer. • Coverage: Most grammar development projects are not based on an investigation of real texts, but start from 'the linguists" text book'. This is different here in that a corpus- based approach to granlmar development has been adopted which is the implementation of the sinlple principle that if a grainnlar is sup- posed to cover reM texts, that the coverage of these texts has to be determined first. The was a corpus investigation in the in the begin- ning, in the course of which tools have been used and developed which allow for automatic and semi-automatic determination of linguistic phenomena. • Conlpleteness: All modules needed from text handling to semantics had to ve developed. This is why this paper does not focus on one single topic, but tries to represent the ulajor achievements of the whole of the system. The paper reports on a text handling component, Two …

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