Incremental search in Constraint Logic Programming

Incremental search consists of adding new constraints or deleting old ones once a solution to a search problem has been found. Although incremental search is of primary importance in application areas such as scheduling, planning, trouble shooting, and interactive problem-solving, it is not presently supported by logic programming languages and little research has been devoted to this topic. This paper presents a scheme to deal efficiently with incremental search problems. The scheme allows the incremental addition and deletion of constraints and is based on re-execution, using parts of computation paths stored during previous computations. The scheme has been implemented as part of the constraint logic programming language CHIP and applied to practical problems. It has shown arbitrarily large (i.e. unbounded) speedups compared with previous approaches on practical problems.