Roland H. C. Yap

Beyond Finite Domains

Unit TVPI constraints are sufficiently expressive for many problems: for example in scheduling and temporal reasoning. We give an algorithm for incremental satisfiability of unit TVPI constraints. Not only is this algorithm efficiently implementable, it also supports efficient implementation of entailment detection, including constraints entailed by disjunctive constraints, and projection. Finally, for use in a CLP system, constraints more general than unit TVPI must be handled, though not necessarily in a complete way. Our algorithm naturally extends to (non-unit) TVPI constraints, and it can be augmented with a bounds-propagation technique for constraints more general than TVPI. An implementation of the solver is underway as part of the continuing development of CLP(R) [9].

A methodology for managing hard constraints in CLP systems

In constraint logic programming (CLP) systems, the standard technique for dealing with hard constraints is to delay solving them until additional constraints reduce them to a simpler form. For example, the CLP (7?) system delays the solving of nonlinear equations until they become linear, when certain variables become ground. In a naive implement ation, the overhead of delaying and awakening constraints could render a CLP system impractical. In this paper, a framework is developed for the specification of wakeup degrees which indicate how far a hard constraint is from being awoken. This framework is then used to specify a runtime structure for the delaying and awakening of hard constraints. The primary implementation problem is the timely awakening of delayed constraints in the context of temporal backtracking, which requires changes to internal data structures be reversible. This problem is resolved efficiently in our struct ure, Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice end the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to rewblish, reauires a fee andlor snecific r)ermission. @“l 991 ACM O-89791 -4i8-7/

Projecting CLP( R ) constraints

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An Optimizing Compiler for CLP(R)

1 .50 1 [ I Proceedings of the ACM SIGPLAN ’91 Conference cm I 1

Constraint Logic Programming and Option Trading

AbstractThe presentation of constraints in a usable form is an essential aspect of Constraint Logic Programming (CLP) systems. It is needed both in the output of constraints, as well as in the production of an internal representation of constraints for meta-level manipulation. Typically, only a small subset

The CLP(R) Programmer's Manual Version 1.2

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Proceedings of the Second Asian Computing Science Conference on Concurrency and Parallelism, Programming, Networking, and Security

of the variables in constraints is of interest, and so an informal statement of the problem at hand is: given a conjunction