Sentence disambiguation by document oriented preference sets

2. The concept of D o P S 1. I n t r o d u c t i o n Ambiguity in sentence interpretation is a major problem in natural language processing(NLP). Conventional NLt' systems often use ad hoc or extremely large knowledgebases (pragmatic / semantic / commonsense) to eliminate ambiguities. Such syslems are too slow and sometimes provide iacomplete analyses. They have the further handicap lhat very large knowledgebases are t~eeded. Asking the user for confirmation [Nishida 1982] is a practical solution to get correct parse-trees, but this confirmation is ~ot useful l'or further computations. A practical NLP system should produce accurate results automatically while using a simple method and simple knowledge. Preference models [Petitpierre 1987, Fass 1983, Schubert 1984], such as preference semantics, scoring, and syntactic preference are good candidates for a practical NLP system, because these models utilize simple readymade knowledge like semantic markers or case frame dictionaries. The most difficult problem with preference models is the selection of the most appropriate preference knowledge that will induce a correct interpretation. However, preference knowledge extracted from a large corpus or an on-line dictionary [Jensen 1987] induces preference knowledge conflicts which block complete disambiguation. Syntact ic rules are capable of producing many sentence parse -trees. These parse-trees are syntactically correct, but most are incorrect from the view points of semantic meaning, contextual meaning, common-sense, specific field knowledge. It is necessary to use appropriate knowledge (semantic / contextual / commonsense / specific field) to eliminate the incorrect interpretations. For example, consider passage 1 of Figure 1. There are two possible interpretations for the gerund-phrase attachment. (1) The power supply(~u-it,b for charging ~ t t ~ ravine a volta~e-temr~erature coefficient .... ... (Passage 1;begining of target sentence) the voltage-temperatm'e coefficient of being charged .... !.. ~1' (Passage 2;part of target sentence)