Understanding of time constituents in spoken language dialogues

The analysis and interpretation of time constituents is a rather complex enterprise, since diverse time constituents are distributable in variable positions within an utterance. The first step in order to manage this complexity and variability is the syntactic analysis at phrase structure level. Within a utterance each time constituent is analyzed independently and tested for its syntactic coherence. A semantic interpretation of the time constituent has to follow. The second step consists of the analysis and interpretation at sentence structure level. The time interpretations need to be tested for consistency and merged into a single representation. Here it is usually possible to resolve ambiguities. As a last step, the interpretations of time constituents have to be merged at dialogue level. Although the system asks the user for verification of the time computed, users do seldom just reply ‘yes’ or ‘no’. Mostly they add new information about time, and sometimes users correct the system’s interpretation without explicit negation. Thus, the merging of time constituents at dialogue level becomes a rather complex issue.