Towards Practical Interval Constraint Solving in Logic Programming

Existing interval constraint logic programming languages, such as BNR Pro-log, work under the framework of interval narrowing and are deecient in solving linear systems, which constitute an important class of problems in engineering and other applications. In this paper, an interval linear equality solver, which is based on generalized interval arithmetic and Gaussian elimination , is proposed. We show how the solver can be adapted to incremental execution and incorporated into a constraint logic programming language already equipped with a non-linear solver based on interval narrowing. The two solvers interact and cooperate during computation, resulting in a practical interval constraint arithmetic language CIAL. A prototype of CIAL, based on CLP(R), is constructed and compared favourably against several major constraint logic programming languages.