Design and Implementation of Extended Boolean and Comparison Operators for Time-Oriented Query Languages
M.A. Bassiouni · The Computer Journal · 1994
Standard Boolean and comparison operators are based on the True/False logic and are therefore not quite suitable for handling events/activities defined over periods of time. In this paper, we generalize the Boolean and comparison operators by allowing their input and output operands to be sets of time intervals. Efficient algorithms for the implementation of the extended operators are presented. The generalized operators can be used to enhance the user interface of time-oriented query languages and allow application users to express their time-related qualifications more succinctly and elegantly. The paper is concluded by examples showing the flexibility of the extended operators in expressing time-related requirements.