Integrating Linguistic and Pragmatic Temporal Information in Natural Language Understanding: the case of "When Sentences"

Abstract

The paper deals with the temporal interpretation of "when sentences" (i.e. sentences composed by a main clause and a secondary clause introduced by a "when" adverbial). It focuses on the problem of integrating "purely linguistic" pieces of temporal information (e.g. the information provided by the anchoring of tense, aspect and aktionsart of the "when" and of the "main" clauses) and "pragmatic" pieces of temporal information (e.g. the knowledge about causal connections among eventualities in the world). The paper describes a modular approach, which is based on the consideration that "pragmatic" and "purely linguistic " pieces of temporal information work independently of each other: the former convey temporal constraints between related eventualities, while the latter provide the perspective of the speaker. Thus independent modules are proposed which (i) represent the causal information concerning the world knowledge and reason with it, extracting the pragmatic temporal constraints among the eventualities "per se" (i .e. regardless of the perspective of the speaker) (ii) determine (considering tense, aspect, aktionsart) the temporal content of the clauses considered in isolation (and, in particular, the speaker's perspective) (iii) anchor the perspectives of the two clauses (iv) propagate the qualitative temporal constraints, integrating "pragmatic" and linguistic information, to arrive at a single, integrated interpretation of the "when sentence" as a whole.