Tabulation for Multi-Purpose Partial Parsing

Efficient partial parsing systems (chunkers) are urgently required by various natural language application areas because these parsers always produce partially parsed text even when the text does not fully fit existing lexica and grammars. Availability of partially parsed corpora is absolutely necessary for extracting various kinds of information that may then be fed into those systems, thereby increasing their processing power. In this paper, we propose an efficient partial parsing scheme, based on chart parsing, that is flexible enough to support both normal parsing tasks and diagnosis in previously obtained partial parses of possible causes (kinds of faults) that led to those partial, instead of complete, parses. Through the use of the built-in tabulation capabilites of the DyALog system, we implemented a partial parser that runs as fast as the best non-deterministic parsers. In this paper we elaborate on the implementation of two different grammar formalisms: Definite Clause Grammars (DCG) extended with head declarations and Bound Movement Grammars (BMG).