tailieunhanh - Báo cáo khoa học: "Repair Strategies for Lexicalized Tree Grammars"

This paper presents a framework for the definition of monotonic repair rules on chart items and Lexicalized Tree Grammars. We exploit island representations and a new level of granularity for the linearization of a tree called c o n n e c t e d routes. It allows to take into account the topology of the tree in order to trigger additional rules. These local rules cover ellipsis and common extra-grammatical phenomena such as self-repairs. First results with a spoken language corpora are presented. . | Proceedings of EACL 99 Repair Strategies for Lexicalized Tree Grammars Patrice Lopez LORIA BP239 54500 Vandoeuvre France lopez@ Abstract This paper presents a framework for the definition of monotonic repair rules on chart items and Lexicalized Tree Grammars. We exploit island representations and a new level of granularity for the linearization of a tree called connected routes. It allows to take into account the topology of the tree in order to trigger additional rules. These local rules cover ellipsis and common extra-grammatical phenomena such as self-repairs. First results with a spoken language corpora are presented. Introduction In the context of spoken task-oriented manmachine and question-answering dialogues one of the most important problem is to deal with spontaneous and unexpected syntactical phenomena. Utterances can be very incomplete and difficult to predict which questions the principle of grammaticality. Moreover large covering grammars are generally dedicated to written text parsing and it is not easy to exploit such a grammar for the analysis of spoken language even if complex syntax does not occur. For such sentences robust parsing techniques are necessary to extract a maximum of information from the utterance even if a complete parsing fails at least all possible constituents . Considering parsing of word-graphs and the large search space of parsing algorithms in order to compute all possible ambiguities the number of partial parses can be very important. A robust semantic processing on these partial derivations would result in a prohibitive number of hypotheses. We argue in this paper that appropriate syntactical constraints expressed in a Lexicalized Tree Grammar LTG can trigger efficient repair rules for specific oral phenomena. First results of a classical grammatical parsing are presented they show that robust parsing need to cope with oral phenomena. We argue then that extended domain of locality and lexicalization of LTG can be .