Integrating world knowledge and linguistic constraints in the temporal interpretation of 'when' sentences

This article focuses on the problem of determining the qualitative temporal constraints between the eventualities described by 'when' sentences. It faces the problem of integrating the purely linguistic temporal constraints provided by the anchoring of aspect and aktionsart of the 'when' clause and of the main clause with the temporal constraints provided by the causal connections constituting the world knowledge. The modular approach we propose is based on the consideration that world knowledge and linguistic tools such as aspect and aktionsart work independently of each other: The former conveys temporal constraints between related eventualities, while the latter provide the temporal perspectives selected by the speaker. Thus, independent modules are proposed which: (1) represent the causal information and reason with it, extracting the qualitative temporal constraints between the eventualities regardless of the temporal perspectives introduced by the descriptions of the speaker; (2) determine (considering aspect and aktionsart) the temporal content of the clauses considered in isolation (and, in particular, the temporal perspectives introduced by the speaker); (3) anchor the temporal perspectives of the main clause and of the 'when' clause; and (4) integrate the qualitative temporal constraints determined by (1), (2), and (3), to arrive at a single, integrated interpretation of the 'when' sentence as a whole.