The implementation of AKL ( FD ) Bj

AKL(FD) is an integration of (an extension of) the nite domain constraint system FD in AKL, a deep concurrent constraint programming language CJH94]. In this paper we describe the implementation of the FD solver and its adaptation to the generic constraint interface of the AGENTS implementation of AKL. We also describe compilation techniques used by the AKL(FD) compiler. 1 Introduction Conceptually, a concurrent constraint programming (CCP SRP91]) language is an ideal vehicle for constraint programming. The expressiveness of the constraint solver can be extended by user-deened entailment-driven propagation rules that execute concurrently and cooperate with the constraint solver. However, to ooer an orthogonal combination of constraint programming with the other paradigms ooered by CCP|concurrent, rela-deep means having a hierarchy of constraint stores, where a computation need not be aaected by the failure of a subordinate store. This makes it possible to have a reactive process/object-oriented top-level in a program, with other encapsulated components performing constraint solving. AKL is a deep CCP language JH91, Jan94] and AKL(FD) is an integration of (an extension of) the indexical-based nite domain constraint system FD VHSD91] in AKL CJH94, Car95]. That AKL(FD) is very expressive and that good performance can be achieved has been argued elsewhere CJH94]. The purpose of the present paper is to give the details of the implementation of the FD solver, which operates in a hierarchy of constraint stores, and its adaptation to the generic constraint interface of the AGENTS implementation of AKL. Our work has four main aspects: (1) Execution of indexicals is optimized. (2) High-level nite domain constraints, such as symbolic and propositional