Compiling and Using Finite-State Syntactic Rules

A language-independent framework for syntactic finlte-state parsing is discussed. The article presents a framework, a formalism, a compiler and a parser for g rammars written in this forrealism. As a substantial example, fragments from a nontrivial finite-state grammar of English are discussed. The linguistic framework of the present approach is based on a surface syntactic tagging scheme by F. Karlsson. This representation is slightly less powerful than phrase structure tree notation, letUng some ambiguous constructions be described more concisely. The finite-state rule compiler implements what was briefly sketched by Koskenniemi (1990). It is based on the calculus of finite-state machines. The compiler t ransforms rules into rule-automata. The run-t ime parser exploits one of certain alternative strategies in performing the effective intersection of the rule automata and the sentence automaton. Fragments of a fairly comprehensive finite-state granmmr of English axe presented here, including samples from non-finite constructions as a demonstration of the capacity of the present formalism, which goes far beyond plain disamblguation or part of speech tagging. The grammar itself is directly related to a parser and tagging system for English created as a part of project SIMPR I using Karlsson's CG (Constraint Grammar) formalism.