New Approaches to Parsing Conjunctions Using Prolog

Abstract

Con junctions are pal'i.icularly diflicult to parse in traditional, phrase-based grammars. This paper shows how a th:f!ercnt reprcsentation, not based on tree structures, ma:·kedly improves the parsing problem for conjunctions . lt modifies the union of phrasc marker model proposed by Goodall [1984], where conjunction is consiclcred as the line;l rization of a three-dim<'nsional union of a non-tree based phra se markcr representation. A PROLOG grammar for conjundions using this new approach is given. It is far simpler and more tr<msparent than a rccent phrase-based extrapo sit.ion parscr conjunctions by Daltl and McCord [1984]. Unlikc the Dahl and McCord or ATN SYSCONJ approach, no special trail machinery is necded for conjnnction, beyond that rcquir ed for an alyz.ing si mple sentences. While of comparable efficiency, thc new approach unifies nnder a singlc analysis a host of relatcd constrnctions: respectively sentcnces, right nodc r aising, or ga pping . Another advantage is that it is also comp letely reversible (without cuts), and therefore can be used to ge nerate sentences.