Constraint Handling Rules - What Else?

September 25, 2015 12:08 PM
What are Constraint Handling Rules (CHR)? The slides of Prof. Thom Frühwirth, keynote at let us know.

Constraint Handling Rules (CHR) is both a versatile theoretical formalism based on logic and an efficient practical high-level programming language based on rules and constraints.

Procedural knowledge is often expressed by if-then rules, events and actions are related by reaction rules, change is expressed by update rules. Algorithms are often specified using inference rules, rewrite rules, transition rules, sequents, proof rules, or logical axioms. All these kinds of rules can be directly written in CHR. The clean logical semantics of CHR facilitates non-trivial program analysis and transformation. About a dozen implementations of CHR exist in Prolog, Haskell, Java, Javascript and C. Some of them allow to apply millions of rules per second. CHR is also available as WebCHR for online experimentation with more than 40 example programs. More than 200 academic and industrial projects worldwide use CHR, and about 2000 research papers reference it.

RuleML 2015 Report

September 13, 2015 3:38 PM
The 9th International Web Rule Symposium ( ) was held in Berlin, Germany, August 2-5. A total number of 94 papers was submitted from which 22 full papers, 1 short paper, 2 keynote papers, 3 track papers, 4 tutorial papers, 6 industry papers, 6 challenge papers, 3 competition papers, 5 PhD papers and 3 poster papers were selected.

The papers where presented in multiple tracks on: Complex Event Processing, Existential Rules and Datalog+/-, Industry Applications, Legal Rules and Reasoning, and Rule Learning.

Following up on previous years, RuleML also hosted the 5th RuleML Doctoral Consortium and the 9th International Rule Challenge as well as the RuleML Competition, which this year was dedicated to Rule-based Recommender Systems on the Web of Data. A new high light of this year's event was the Industry Track introducing six papers describing research work in innovative companies.

New this year was also the joint RuleML / Reasoning Web tutorial day on the first day of RuleML 2015, with four tutorials about the TPTP World by Geoff Sutcliffe, PSOA RuleML by Harold Boley, Rulelog by Benjamin Grosof, and OASIS LegalRuleML by Tara Athan.

This year’s symposium featured three invited/keynote talks:

Very special this year was the great collocation of several events. A total number of 138 registered participants attended the main RuleML 2015 symposium and the affiliated sub-events and co-located Conference on Web Reasoning and Rule Systems ( ), the Reasoning Web Summer School ( ) and the Workshop on Formal Ontologies meet Industry ( ). Additionally, the Conference on Automated Deduction ( ) celebrated its 25th edition with over 200 participants. This "Berlin on Rules" co-location was a great opportunity for the rule-based community to meet with the automated deduction community at one of the several joint social events, such as the joint reception at the Botanic Garden on Monday August 3rd, the joint keynote by Michael Genesereth and the poster session on Tuesday, August 4th, and the joint conference dinner at the Fischerhuette restaurant at the lake Schlachtensee on Wednesday, August 5th.

The welcome address at the reception was given by Ute Finckh-Krämer (Berlin, SPD, member of the German Parliament) followed by Wolfgang Bibel (Univ. Darmstadt) as the invited speaker.

The dinner speech at the Fischerhuette was given by Jörg Siekmann (Univ. Saarbrücken).

The poster session, with 18 posters and demos, was jointly organized as a get-together with the Berlin Semantic Web Meetup with wine, beer and finger food in the green houses of the Computer Science Department at the Freie Universität Berlin. The organizers also used this unique opportunity for a joint public RuleML and RR business meeting and an invited dinner with all chairs, and invited/keynotesspeakers of RuleML, RR, RW, FOMI and CADE.

The additional rich social program, with a bus sightseeing tour to east, west, and downtown Berlin on Saturday, Aug. 1st, a boat sightseeing tour from lake Wannsee to the Reichstag on Sunday, Aug. 2nd , the CADE exhibitions on Wednesday and plenty visits to the various beer gardens, made it a memorable stay in the capital of Germany for the participants.


The RuleML 2015 Best Paper Award was given to Thomas Lukasiewicz, Maria Vanina Martinez, Livia Predoiu, and Gerardo I. Simari for their paper "Existential Rules and Bayesian Networks for Probabilistic Ontological Data Exchange". The 9th International Rule Challenge Award went to Jean-François Baget, Alain Gutierrez, Michel Leclère, Marie-Laure Mugnier, Swan Rocher, Clément Sipieter, for their paper "Datalog+, RuleML and OWL 2: Formats and Translations for Existential Rules".

The winners of the RuleML 2015 Competition Award were Marta Vomlelova, Michal Kopecky, Peter Vojtas, for their paper "Transformation and Aggregation Preprocessing for Top-k Recommendation GAP Rules Induction".

As in previous years, RuleML 2015 was also a place for presentations and face-to-face meetings about rule technology standardizations, which this year covered OASIS LegalRuleML, RuleML 1.02 (Consumer+Deliberation+Reaction), OMG API4KB, OMG SBVR, ISO Common Logic, ISO PSL, and TPTP.

We would like to thank our sponsors, whose contributions allowed us to cover the costs of student participants and invited/keynote speakers.

We would also like to thank all the people who have contributed to the success of this year’s special RuleML 2015 and co-located events, including the organization chairs, PC members, authors, speakers, and participants.