- The CHR 2010 Workshop will be held July 20, 2010 in Edinburgh (Scotland) at the occasion of ICLP 2010 (part of FLoC 2010), the premier international venue for presenting research in logic programming. The first call for papers is available.
- Both the CHR survey and the TKDE article on CHR compilation are accepted for publication. The CHR 2009 workshop paper has been published as well. See the publications page for more details.
- The Sixth International Workshop on Constraint Handling Rules will be held in Pasadena, California at the occasion of the 25th International Conference on Logic Programming. The workshop features six excellent papers, including our own A Proposal for a Next Generation of CHR. We hope to welcome you at the workshop in July!
- JCHR version 2 is in the make! Previews of underlying ideas and supported features can be found in the following draft publications: Efficient Lazy Evaluation of Rule-Based Programs, submitted to Special Issue of IEEE Transactions on Knowledge and Data Engineering on Rule Representation, Interchange and Reasoning in Distributed, Heterogeneous Environments; and A Proposal for a Next Generation of CHR, submitted to the CHR 2009 workshop.
- A paper presenting the Eclipse IDE for JCHR developed by Slim Abdennadher and Shehab Fawzy of the German University of Cairo was presented at WLP '08.
- This december Peter Van Weert will be presenting Optimization of CHR Propagation Rules at the 24th International Conference on Logic Programming (ICLP'08) in Udine, Italy. Other CHR papers at this years' ICLP are Termination Analysis of CHR revisited by Paolo Pilozzi and Daniel De Schreye, and Transactions in Constraint Handling Rules by Tom Schrijvers and Martin Sulzmann. We hope to see you there!
- References to several recent publications on JCHR added.
We added a new, thorough bibliography
of over 180 recent publications to the CHR website. It covers a
wide range of CHR related research areas, from semantics and
analysis to systems, extensions and applications.
The bibliography is originally based on As Time Goes By: Constraint Handling Rules -- A Survey of CHR Research from 1998 to 2007. A draft of the survey is also available.
- K.U.Leuven JCHR version 1.6.0 has been released. The new version is typically almost twice as fast as the previous versions! Code generation has been rewritten from scratch, new analyses and optimizations have been added, stack overflow issues have been eliminated, and much, much more. Debug and trace support no longer works in this release, but will be restored in an upcomming version.
- K.U.Leuven JCHR appears on 99-bottles-of-beer.net, a website holding a collection of the Song 99 Bottles of Beer, programmed in more than 1000 different programming languages.
Version 1.5.1 adds some
more static analysis (on reactiveness and propagation history), and
improves the encapsulation of non-
- Already has the next version been released! Version 1.5.0 continues along the same lines as its predecessor, version 1.4.0: many new, powerful static analyses (never stored, set semantics, observation, ...), several new syntactical features (packages, access modifiers, ...) and enhancements (improved infix identifiers, new built-in constraints, ...), and much more. The manual [ps, pdf] has also been updated to the new version. Not only does this new version have many interesting new features, it also is considerably faster then before in many cases, and it includes some important bug fixes! So we encourage everybody to try out the new version as soon as possible!
- The manual [ps, pdf] is now fully up to date with the newest 1.4.0 release.
- The long-awaited version 1.4.0 is released and ready for download! The version history lists many of the changes made over the last couple of months: an improved command line interface, syntactical enhancements, nifty implicit variable declarations, handy static imports of members, helpful singleton variable detection, join order and subsumption analysis, a handy trace debugger, and much more!
- The JCHR user's manual is really starting to look nice. A manual is never truely finished though, so we welcome any comments and suggestions. The latest (draft) version can always be found on the documentation page.
Eric Lindahl has taken an interest in JCHR and put a copy of the project on SourceForge.net, the world's largest Open Source software development web site. Have a look at the project's home page and its wiki pages.
It is probably too soon to know where this is going, but recent private communication with Eric sounds very promising indeed:
I think, at least, I could provide operational support for fit-and-finish, testing, Eclipse integration, scripting, [...] tool support and test cases, with fixes & enhancements [...] One of my hopes is to provide a world-class rules engine to 'compete' with Drools/JBoss Rules With book and movie deals to follow [...] My longer term goal is to provide a rules language extension to a good scripting engine, like BeanShell.
At the moment, Eric has already added the package keyword to the JCHR language, and created a scripting shell to compile .jchr files (doesn't this screenshot look nice?). His version of the code, which builds on our 1.3.3 version, is available for download from the home page.
We are very excited about this new and unexpected development, or should we say developper, and we hope this can be a start of a fruitful collaboration.
- The K.U.Leuven JCHR system was mentioned in two related newsletter articles: one from the association for constraint programming: CP News, Vol.2 n.2 in an article written by Bart Demoen, giving an overview of the K.U.Leuven CHR research; and one from the association of logic programming: the ALP Newletter, Vol.19 n.3, in an article by Tom Schrijvers, providing an overview of the K.U.Leuven CHR system.
- A Sudoku program was written by students of the university of Ulm using the K.U.Leuven JCHR System. This very nice Sudoku applet is available on the CHR homepage (under example programs).
- We have revived the work on the manual. The most recent draft version will always be available from the Documentation page. All comments are welcome. Note that the manual already mentions features and properties of the upcoming 1.4.0 version, which will certainly not be released before september. Most of what is in the manual is correct for the current stable version though.
- The Third Workshop on Constraint Handling Rules (CHR 2006) was held in Venice, Italy, at the occasion of ICALP 2006, and was once again a big success. The workshop proceedings have been published as a technical report.
- The Third Workshop on Constraint Handling Rules (CHR 2006) will be held in Venice, Italy, at the occasion of ICALP 2006, on July 9. We refer to the website for more information (including an overview of accepted papers). Registration for the CHR 2006 workshop is possible through the ICALP/PPDP/LOPSTR'06 and affiliated Workshops registration page. Early registration ends on June 10.
A seminar day on Constraint Handling Rules will be held in Leuven.
Researchers from the Declarative Languages and Artificial
Intelligence group (DTAI) of the K.U.Leuven, and
the research group of the University of Ulm headed by Thom
Früh (creator of CHR) will present the latest developments of
the CHR language and future research topics.
More information can be found here.
- The K.U.Leuven JCHR website has switched to Google Analytics. The old webstats4u counter has been removed, because it unfortunately showed pop-up ads from time to time. Since its installation on October 17 2005 it had registered 666 visitors (sic: read more about the number 666 here or here) from all over the world (43 countries in all continents but Antarctica). We strive to do even better in the future!
- Some important bug fixes, mainly to the runtime code [Version History].
- The WebCHR Interactive Demo has moved to its new location in Ulm. Experiment with over 40 constraint solvers and programs or write your own.
- Some handy new features and improvements have been introduced in version 1.3.2.
Version 1.3.1 has been
released. This version includes several important bug fixes in the
runtime code: some benchmarks now run twice as fast! A very good
reason indeed to update to the new version. Also, logical variables
now have the type
Logical<Type>, saving more then 50% of the letters you have to type declaring them. Many more improvements have been made: more information can be found on the Version History page.
- A research position is available for Ph.D. students or postdocs at the Faculty of Computer Science, University of Ulm, Department of Software Engineering and Compiler Construction in the area of Constraint Handling Rules (CHR).
- The Third Workshop on Constraint Handling Rules, Venice, Italy (CHR 2006) is to be held at the occasion of ICALP 2006 on July 9. The call for papers is available here.
- A new year, a new logo, a new website! Happy 2006 everybody!
- Release of version 1.3.0, with added support for anonymous variables in rule heads and many bug fixes.
- Two new example handlers have been added to the site: dijkstra and fib_heap. These examples, adapted from Dijkstra's algorithm with Fibonacci heaps: an executable description in CHR by Jon Sneyers, Tom Schrijvers, and Bart Demoen [report], illustrate most of the more recent features of the K.U.Leuven JCHR System: anonymous variables, JCHR constraints as built-in constraints for other handlers, passive pragmas, etc.
Version 1.2.0 is released. As of this version existing
constraint handlers can be used as built-in constraints for new
handlers. Their constraints are considered built-in tell
constraints there and can therefore only be used in rule-bodies of
the new handler. Also,
SharedStateclasses are now called
Handlerclasses (and include tell-methods), which will unfortunately necessitate the refactoring of existing code. For more information please consult the Version History.
- The main (and in fact only for the time being) JCHR contributor Peter Van Weert has decided (after a short detour) to return to the CHR research community, starting from January 1. This more than likely means that he will be able to spend some more time on extending and improving the system. If there are interesting features you would like to see in the system, please let us know!
- The K.U.Leuven JCHR System was
mentioned in Dijkstra's
algorithm with Fibonacci heaps: an executable description in
CHR by Jon Sneyers, Tom Schrijvers, and Bart Demoen
Note that our most recent version does contain
pragma passivedirectives like the ones used for the SICStus and YAP versions, which might improve the performance a bit more.
Version 1.1.4 released. Yet another bug has been fixed.
Comparatorbuilt-in solvers will now work as they were intended. [Version History]
- Version 1.1.3 released (bug fix). Thanks to Armin Wolf and his students for reporting some more bugs. But this time we managed to find one ourselves too! [Version History]
- Version 1.1.2 released (bug fix). Thanks to Armin Wolf and his students for (again) sending us bug-reports! [Version History]
- Version 1.1.1 released. Main improvements are passive pragmas and a more user-friendly constraint store. Read more about it in the Version History.
- Version 1.1.0 released (Version History). Mergesort example and benchmark added to the website.
- A first, very incomplete draft of a manual is available. This is still very much work in progress and will be updated regularly (to be read as: some day, maybe...)
- Website has been moved to his (most probably) final location: http://www.cs.kuleuven.be/~petervw/JCHR/
- Version 1.0.3 released (bug fix) (Version History). Also, we ran a spell checker on the website revealing some silly mistakes.
- Slides CHR 2005 presentation put online [PowerPoint Slide Show]
- The K.U.Leuven JCHR System was presented at the Second Workshop on Constraint Handling Rules (CHR 2005) by Peter Van Weert, held at Sites (Spain) at the occasion of ICLP'05.
- Version 1.0.2 released (bug fix) (Version History)
- Version 1.0.1 released (bug fix) (Version History)
- CHR 2005 accepted our paper on the K.U.Leuven JCHR System. The system will be presented at the Second Workshop on Constraint Handling Rules (CHR 2005), to be held at Sites (Spain) at the occasion of ICLP'05.
- Paper on the K.U.Leuven JCHR System submitted to the Second Workshop on Constraint Handling Rules (CHR 2005). [paper]
- July 2005
- Peter Van Weert gets 18.5 out of 20 on his Master's thesis and graduates with the greatest distinction (summa cum laude) with felicitations of the jury.
- May 18 2005
- Peter Van Weert finishes and hands in his Master's thesis at the department of computer science of the K.U.Leuven (Belgium). [thesis]