The Constraint Handling Rules (CHR) language is a declarative concurrent committed-choice constraint logic programming language consisting of guarded rules that transform multisets of relations called constraints until no more change occurs. The CHR language saw the light more than 15 years ago. Since then, it has become a major declarative specification and implementation language for constraint-based algorithms and applications. In recent years, five workshops on constraint handling rules have spurred the exchange of ideas within the CHR community, which has led to increased international collaboration, new theoretical results and optimized implementations. The aim of this volume was to attract high-quality research papers on these recent advances in Constraint Handling Rules. The 7 papers presented together with an introductory paper on CHR cover topics on search, applications, theory, and implementation of CHR. The ConstraintHandling Rules (CHR) languagecameto life morethan 15 years ago.Sincethen,ithasbecomeamajordeclarativespeci?cationandimplemen- tion language for constraint-based algorithms and applications. In recent years, the ?ve Workshops on Constraint Handling Rules have spurred the exchange of ideas within the CHR community, which has led to increased international collaboration, new theoretical results and optimized implementations. The aim of this volume of Lecture Notes in Ariti?cial Intelligence was to attract high-quality research papers on these recent advances in CHR. The 8 papersinthis issuewereselectedfrom11submissionsaftercarefulreviewingand subsequent revisions. Each paper was reviewd by three reviewers. The accepted papers represent some of the research teams on CHR around the world. It is not by accident that the currently most active research group is featured here with three articles. We also would have liked to see contributions from other CHR teams, but space is limited and the reviewers took their job seriously. After an introductory article that foreshadows an upcoming monograph on CHR, the accepted papers span a range of current research topics in the CHR community. It goes from extending the CHR language with search facilities and the related adaptive framework, and from generating rules from speci?cations of constraint solvers to implementing abductive probabilistic reasoning. They cover the theory that is a compositional semantics for CHR and ?nally describe e?cient implementations of CHR in traditional mainstream programming l- guages and compiler optimizations in the context of the re?ned semantics of CHR. Wewouldliketothanktheauthorsofsubmittedpapersandthemanyrevi- ers for their contribution in making this collection of research papers possible. Welcome to constraint handling rules / Thom Frühwirth Search. A flexible search framework for CHR / Leslie De Koninck, Tom Schrijvers, and Bart Demoen. Adaptive CHR meets CHR[superscript v] : an extended refined operational semantics for CHR[superscript v] based on justifications / Armin Wolf, Jacques Robin, and Jairson Vitorino Applications. Constructing rule-based solvers for intentionally-defined constriants / Ingi Sobhi, Slim Abdennadher, and Hariolf Betz. Implementing probabilistic abductive logic programming with constraint handling rules / Henning Christiansen Theory. A compositional semantics for CHR with propagation rules / Maurizio Gabbrielli, Maria Chiara Meo, and Paolo Tacchella Implementation. CHR for imperative host languages / Peter Van Weert ... [et al.]. Guard reasoning in the refined operational semantics of CHR / Jon Sneyers, Tom Schrijvers, and Bart Demoen. Front Matter....Pages - Welcome to Constraint Handling Rules....Pages 1-15 A Flexible Search Framework for CHR....Pages 16-47 Adaptive CHR Meets CHR ∨ ....Pages 48-69 Constructing Rule-Based Solvers for Intentionally-Defined Constraints....Pages 70-84 Implementing Probabilistic Abductive Logic Programming with Constraint Handling Rules....Pages 85-118 A Compositional Semantics for CHR with Propagation Rules....Pages 119-160 CHR for Imperative Host Languages....Pages 161-212 Guard Reasoning in the Refined Operational Semantics of CHR....Pages 213-244 Back Matter....Pages -
