Introduction to the Special Issue on Constraint Handling Rules

摘要

During the last decade, Constraint Handling Rules (CHR) have become a major specification and implementation language for logical, constraint-based algorithms and intelligent applications (as witnessed for example by several hundred publications available online that mention CHR). Algorithms are often specified using inference rules, rewrite rules, sequents, proof rules, or logical axioms that can be almost directly written in CHR. In recent years, CHR have been successfully used 1. as general purpose concurrent constraint language with ask and tell 2. as fairly efficient production rule system 3. as special kind of theorem prover with constraints 4. as system combining forward and backward chaining 5. for bottom-up evaluation with integrity constraints 6. for top-down evaluation with tabulation 7. for combining deduction, abduction, and constraints 8. as high-level language for manipulating attributed variables 9. for parsing with executable grammars 10. for multi-set rewriting and transformations.