New Approaches to Parsing Conjunctions Using Prolog

Conjunctions arc particularly difficult to parse in tra¬ditional, phrase-based grammars. This paper shows how a different representation, not based on tree structures, markedly improves the parsing problem for conjunctions. It modifies the union of phrase marker model proposed by Qoodall [1081), where conjunction is considered as the lin¬earization of a three-dimensional union of a non-tree based phrase marker representation. A PU.OLOC grammar for con¬junctions using this new approach is given. It is far simpler and more transparent than a recent phrase-based extra¬position parser conju/ictious by Dahl and McCord [l934|. Unlike the Dahl and McCord or ATN SYSCONJ approach, no special trail machinery in needed for conjunction, be¬yond that required for analyzing simple sentences. While of comparable efficiency, the new approach unifies tinder a single analysis a host of related constructions: respectively sentences, right node raising, or gapping. Another advan¬tage is that it is also completely reversible (without cuts), and therefore can be used to generate sentences.