CHR Research Group

Constraint Handling Rules (CHR) is a concurrent committed-choice constraint logic programming language consisting of guarded rules that transform multi-sets of atomic formulas (constraints) until exhaustion. It was designed by Thom Fruehwirth in 1991. CHR can embed many rule-based formalisms and systems, and it can describe algorithms in a compact declarative way without compromising efficiency. The clean semantics of CHR ensures that several desirable properties hold for CHR programs and also facilitates sophisticated program analysis. CHR libraries exist for Prolog, Haskell, Java, Javascript, Python and C. CHR is also available online for experimentation with many example programs. More than 250 academic and industrial projects worldwide use CHR, and about 2500 research papers reference it.

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2023

100.
Rechenberger, Sascha; Frühwirth, Thom
FreeCHR: An Algebraic Framework for CHR Embeddings
7th International Joint Conference on Rules and Reasoning (RuleML+RR '23), Oslo, Norway
October 2023
DOI:10.1007/978-3-031-45072-3_14
ISBN:978-3-031-45072-3
99.
Rechenberger, Sascha; Frühwirth, Thom
FreeCHR: An Algebraic Framework for CHR-Embeddings
2023
DOI:10.48550/arXiv.2306.00642
98.
[en] Rechenberger, Sascha; Frühwirth, Thom
FreeCHR: An Algebraic Framework for~CHR-Embeddings
In Fensel, Anna and Ozaki, Ana and Roman, Dumitru and Soylu, Ahmet, Editor, Rules and ReasoningfromLecture Notes in Computer Science, Page 190—205
In Fensel, Anna and Ozaki, Ana and Roman, Dumitru and Soylu, Ahmet, Editor
Publisher: Springer Nature Switzerland, Cham
2023
DOI:10.1007/978-3-031-45072-3_14
ISBN:978-3-031-45072-3
97.
[en] Rechenberger, Sascha; Frühwirth, Thom
FreeCHR: An Algebraic Framework for~CHR-Embeddings
In Fensel, Anna and Ozaki, Ana and Roman, Dumitru and Soylu, Ahmet, Editor, Rules and ReasoningfromLecture Notes in Computer Science, Page 190—205
In Fensel, Anna and Ozaki, Ana and Roman, Dumitru and Soylu, Ahmet, Editor
Publisher: Springer Nature Switzerland, Cham
2023
DOI:10.1007/978-3-031-45072-3_14
ISBN:978-3-031-45072-3
96.
Rechenberger, Sascha; Frühwirth, Thom
FreeCHR: An Algebraic Framework for CHR-Embeddings
2023
DOI:10.48550/arXiv.2306.00642

2020

95.
Frühwirth, Thom
Repeated Recursion Unfolding for Super-Linear Speedup within Bounds
Pre-Proceedings of the 30th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2020)
September 2020
File:https://arxiv.org/abs/2009.05314

2019

94.
Frühwirth, Thom
Justifications in Constraint Handling Rules for Logical Retraction in Dynamic Algorithms: Theory, Implementations, and Complexity
Journal Fundamenta Informaticae
2019
Publisher: IOS Press

2018

93.
Frühwirth, Thom
The Computer Art of Mason's Mark Design with VanDeGraphGenerator
Publisher: BOD
October 2018
ISBN:9783752842975
File:https://books.google.de/books?id=w3hoDwAAQBAJ
92.
Gall, Daniel; Frühwirth, Thom
An Operational Semantics for the Cognitive Architecture ACT-R and its Translation to Constraint Handling Rules
ACM Transactions on Computational Logic (TOCL), 19 (3)
September 2018
DOI:10.1145/3218818
File:https://arxiv.org/abs/1702.01606
91.
Frühwirth, Thom
Implementation of Logical Retraction in Constraint Handling Rules with Justifications (full version)
In Dietmar Seipel, Michael Hanus, Salvador Abreu, Editor, Declarative Programming and Knowledge Management, Proceedings of the Conference on Declarative Programming DECLARE 2017, Revised Selected PapersVolume10997, Page 37--52
DECLARE 2017
Würzburg
17.-22.09.2017
In Dietmar Seipel, Michael Hanus, Salvador Abreu, Editor
Publisher: Springer
September 2018
DOI:10.1007/978-3-030-00801-7_3
File:pdfhttp://www.informatik.uni-ulm.de/pm/mitarbeiter/fruehwirth/drafts/chr-just-impl-final-full.pdf