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This paper describes a compositional semantics for temporal expressions as part of the meaning representation language (MRL) of the JANUS system, a natural language understanding and generation system under joint development by BBN Laboratoires and the Information Sciences Institute. 1 The analysis is based on a higher order intansional logic described in detail in Hinrichs, Ayuso and Scha (1987). Temporal expressions of English are translated into this language as quantifiers over times which bind temporal indices on predicates. The semantic evaluation of time-dependent predicates is defined relative to a set of discourse contexts, which, following Reichenbach (1947), include the. | A COMPOSITIONAL SEMANTICS OF TEMPORAL EXPRESSIONS IN ENGLISH Erhard w. Hinrichs BBN Laboratories Inc. 10 Moulton St. Cambridge MA 02238 Abstract This paper describes a compositional semantics for temporal expressions as part of the meaning representation language MRL of the JANUS system a natural language understanding and generation system under joint development by BBN Laboratoires and the Information Sciences Institute.1 The analysis is based on a higher order intensional logic described in detail in Hinrichs Ayuso and Scha 1987 . Temporal expressions of English are translated into this language as quantifiers over times which bind temporal indices on predicates. The semantic evaluation of time-dependent predicates is defined relative to a set of discourse contexts which following Reichenbach 1947 include the parameters of speech time and reference time. The resulting context-dependent and multi-indexed interpretation of temporal expressions solves a set of well-known problems that arise when traditional systems of tense logic are applied to natural language semantics. Based on the principle of rule-to-rule translation the compositional nature of the analysis provides a straightforward and well-defined interface between the parsing component and the semantic interpretation component of JANUS. 1 Introduction JANUS is a natural language understanding and generation system which allows the user to interface with several knowledge bases maintained by the US NAVY. The knowledge bases contain among other things information about the deployment schedules locations and readiness conditions of the ships in the Pacific Fleet. 1 a. Did the admiral deploy the ship b. Which C3 ships are now C4 c. When will Vincent arrive in Hawaii d. Who was Frederick s previous commander As the sample queries in 1 demonstrate much of The work presented here was supported under OARPA contract N00014-85-C-0016. The views and conclusions contained in this document are those of the authors and
