Semantics of temporal constrained objects

Abstract

This paper presents the declarative and operational semantics for the paradigm of temporal constrained objects (TCOB). This modeling paradigm is an extension of basic constrained objects where objects specify the structure of a system and constraints specify its behavior. Temporal constrained objects have been shown to provide a clear and high-level declarative specification of the time-dependent behavior of complex dynamic systems. Two key features of this paradigm are series variables and metric temporal operators. The main contribution of this paper lies in showing how we can define the semantics of temporal constrained objects in terms of a new paradigm called temporal constraint logic programs (TCLP), which extend temporal logic programs with constraint-solving. Compared with the several other logical languages incorporating constraints and temporal logic, the TCLP paradigm offers a clear and direct way of translating temporal constrained object programs using three simple temporal predicates: first p, next p, and prev p. The key approach is to map each class in a TCOB program to a predicate in the TCLP paradigm. Thus, the semantics of recursively defined classes is expressed in terms of the semantics of recursively defined predicates, a well-understood topic. Given the close connections between TCLP and CLP, we take advantage of the semantics of CLP for providing the declarative and operational semantics of TCLP and thereby also of temporal constrained objects.