Soft Constraint Propagation and Solving in Constraint Handling Rules

Soft Constraint Propagation and Solving in Constraint Handling Rules

Soft constraints are a generalization of classical constraints, where constraints and/or partial assignments are associated to preference or importance levels, and constraints are combined according to combinators which express the desired optimization criteria. Constraint Handling Rules (CHR) constitute a high-level natural formalism to specify constraint solvers and propagation algorithms. In...

Soft Constraint Propagation and Solving inConstraint Handling

Compiling Constraint Handling Rules

We introduce the most recent and advanced implementation of CHR which improves both on previous implementations (in terms of completeness, ex-ibility and eeciency) and on the principles that should guide such an implementation. The idea is to have three rather independent phases of the compiler that utilize templates to generate the code and macros to specialize it. Moreover, our new implementa...

Probabilistic Constraint Handling Rules

Classical Constraint Handling Rules (CHR) provide a powerful tool for specifying and implementing constraint solvers and programs. The rules of CHR rewrite constraints (non-deterministically) into simpler ones until they are solved. In this paper we introduce an extension of Constraint Handling Rules (CHR), namely Probabilistic CHRs (PCHR). These allow the probabilistic “weighting” of rules, sp...

Constraint Handling Rules

Constraint Handling Rules (CHR) is both a theoretical formalism based on logic and a practical programming language based on rules. This book, written by the creator of CHR, describes the theory of CHR and how to use it in practice. It is supported by a website containing teaching materials, online demos, and free downloads of the language. After a basic tutorial, the author describes in detail...