wpu.nu

Sida:Ann-1983 JBC25001-00 James Allen - Maintaining knowledge about temporal intervals.pdf/2

Från wpu.nu

Den här sidan har inte korrekturlästs


Maintaining Knowledge about Temporal Intervals

James F. Allen The University of Rochester

. Abstract

The problem of representing temporal knowledge arises in many areas of computer science. In applications in which such knowledge is imprecise or relative, current representations based on date lines or time instants are inadequate. An interval-based temporal logic is iotroduced, logether with a computationally effective reasoning algorithm based on constraint propagation. This system is notable in offering a delicate balance between expressive power and the efficiency of its deductive engine.

A notion of reference intervals is introduced which captures the tenporal hierarchy implicit in many domains, and which can be used to precisely control the amount of deduction performed automatically by the system. Examples are provided for a data base containing historical dala, a data base used for modeling processes and process interaction, and a data base for an interactive system where the present moment is continually being updated.

CR Categories and Subject Descriptors: 1.2.4 (Knowledge Representation]: Representation--time, temporal representation; 1.2.3 [Deduction and Theorem Proving]: deduction--constraint propagation, temporal reasoning; H.3.3 [Information Search and Retrieval): Clustering, Retrieval Models

General Terms: Algorithms Additional Key Words and Phrases: temporal interval, interval reasoning, interval representation

Author's address: Computer Science Department, Universily of Rochester, Rochester, NY, 14627.

The research described in this paper was supported in part by the National Science Foundation under Grants IST-80-12418 and IST-8210564, and in part by the Office of Naval Research under Grant N00014-80-C-0197,