Sequences constraint solving in constraint logic programming

This paper deals with consistency techniques over sequences constraints embedded in Constraint Logic Programming CLPS. CLP Sequences constraints are defined over Hereditarily Homogeneous Finite Sets HHFS built on atomic elements to characterise a family of admissible sequences. The relations we are dealing with are classical sets relations (∈,⊂,=,≠) and sequencing relations as potential, metric and range constraints. We define the semantics of these relations with a characteristic range function. The consistency techniques used are incremental reduction of the normal form based on a tree like representation called P-Q-R trees. This allows us to reduce the set of admissible sequences before generating solutions