Spatio-temporal Indexing in Database Semantics

Abstract

In logic, the spatio-temporal location of a proposition is characterized precisely within a Cartesian system of space and time coordinates. This is suitable for characterizing the truth value of propositions relative to possible worlds, but not for modeling the spatio-temporal orientation of natural cognitive agents.¹ This paper presents an alternative approach to representing space and time. While on the same level of abstraction as the logical approach, it is designed for an anal- ysis of spatio-temporal inferences in humans. Such an analysis is important for modeling natural language communication because spatio-temporal information is constantly coded into language by the speaker and decoded by the hearer. Starting from the spatio-temporal characterization of direct observation in cogni- tive agents without language, the speaker’s coding of spatio-temporal information into language is analyzed, followed by the hearer’s reconstruction of this location. These procedures of transferring spatio-temporal information from the speaker to the hearer are embedded in the general structure of database semantics.

The analysis of time in tensed predicate calculus (TPL) is critically reviewed in Kamp & Reyle 1993, Vol. 2, p. 483-510. Their own approach, called discourse representation theory (DRT), however, has “no conclusive answers to these questions, and presumably there are no clear, non-stipulative answers to be had” (op. cit. p. 666). From the viewpoint of database semantics, this is not surprising because DRT is itself a variant of model-theoretic semantics.