Modularity and information content classes in principle-based parsing

• Authors: Paola Merlo
• Venue: Computational Linguistics
• Year: 1995

In recent years models of parsing that are isomorphic to a principle-based theory of grammar (most notably Government and Binding (GB) Theory) have been proposed (Berwick et al. 1991). These models are natural and direct implementations of the grammar, but they are not efficient, because GB is not a computationally modular theory. This paper investigates one problem related to the tension between building linguistically based parsers and building efficient ones. In particular, the issue of what is a linguistically motivated way of deriving a parser from principle-based theories of grammar is explored. It is argued that an efficient and faithful parser can be built by taking advantage of the way in which principles are stated. To support this claim, two features of an implemented parser are discussed. First, configurations and lexical information are precompiled separately into two tables (an X; table and a table of lexical co-occurrence) which gives rise to more compact data structures. Secondly, precomputation of syntactic features (θ-roles, case, etc.) results in efficient computation of chains, because it reduces several problems of chain formation to a local computation, thus avoiding extensive search of the tree for an antecedent or extensive backtracking. It is also shown that this method of building long-distance dependencies can be computed incrementally.