tailieunhanh - Báo cáo khoa học: "TEMPORAL RELATIONS: REFERENCE OR DISCOURSE COHERENCE?"

The temporal relations that hold between events described by successive utterances are often left implicit or underspecified. We address the role of two phenomena with respect to the recovery of these relations: (1) the referential properties of tense, and (2) the role of temporal constraints imposed by coherence relations. We account for several facets of the identification of temporal relations through an integration of these. | TEMPORAL RELATIONS REFERENCE OR DISCOURSE COHERENCE Andrew Kehler Harvard University Aiken Computation Laboratory 33 Oxford Street Cambridge MA 02138 kehler @ das. Abstract The temporal relations that hold between events described by successive utterances are often left implicit or underspecified. We address the role of two phenomena with respect to the recovery of these relations 1 the referential properties of tense and 2 the role of temporal constraints imposed by coherence relations. We account for several facets of the identification of temporal relations through an integration of these. Introduction Tense interpretation has received much attention in linguistics Partee 1984 Hinrichs 1986 Nerbonne 1986 inter alia and natural language processing Webber 1988 Kameyama et al. 1993 Lascarides and Asher 1993 inter alia . Several researchers Partee 1984 Hinrichs 1986 Nerbonne 1986 Webber 1988 have sought to explain the temporal relations induced by tense by treating it as anaphoric drawing on Reichenbach s separation between event speech and reference times Reichenbach 1947 . Specifically to account for the forward progression of time induced by successive simple past tenses in a narrative they treat the simple past as referring to a time evoked by a previous past tense. For instance in Hinrichs s 1986 proposal accomplishments and achievements1 introduce a new reference point that is temporally ordered after the time of the event itself ensuring that two consecutive accomplishments or achievements in a discourse are always ordered in a temporal sequence. On the other hand Lascarides and Asher 1993 take the view that temporal relations are resolved purely as a by-product of reasoning about coherence relations holding between utterances and in doing so argue that treating simple and complex tenses as anaphoric is unnecessary. This approach parallels the treatment of pronoun resolution espoused by Hobbs 1979 in which pronouns are modeled as free variables .