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Extending Unification Formalisms

Gregor Erbach; Mark van der Kraan; Suresh Manandhar; Herbert Ruessink; Craig Thiersch; Wojciech Skut
CLAUS-Report, Universität des Saarlandes, Vol. 62, 5/1995.


This paper describes some of the results of the project LRE-61-061: The Reusability of Grammatical Resources. The aim of the project is to extend unification formalisms with notational devices and constraint solvers in order to facilitate the development of reusable grammars. Work covers both the theoretical description of the extensions as well as the practical implementation. The project took the Advanced Linguistic Engineering Platform (ALEP) as its starting point. ALEP was designed to allow for two levels of extension: additional syntactic expressions "syntactic sugar" and external specialised constraint solvers. The syntactic additions to ALEP comprise LFG coherence and completeness and an extended notation for phrase-structure rules. The project has developed solvers for set constraints and set operations, linear precedence constraints and for implicational or guarded constraints.

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