Comments for Constraint Programming Standardization Blog http://cpstandard.wordpress.com Maintained by Jacob Feldman Tue, 30 Apr 2013 21:32:58 +0000 hourly 1 http://wordpress.com/ Comment on JSR-331 in different JVM languages by jacobfeldman http://cpstandard.wordpress.com/2013/04/30/jsr-331-in-different-jvm-languages/#comment-1298 Tue, 30 Apr 2013 21:32:58 +0000 http://cpstandard.wordpress.com/?p=200#comment-1298 Hi Pierre,
We certainly can do it. However, I expect to add an implementation of the Problem’s methods storeToXML() and loadFromXML() to the common JSR331 support library. It will use the MiniZinc format. Choco 3 already has such an implementation now and hopefully they will share it with us soon. JaCoP has its own MiniZinc interface as well. So, when we have one common interface, all JSR331-compliant solvers will be able to participate in MiniZinc competition. Let me know if/when you are ready to create an OscaR-based implementation of JSR331 – I’d be glad to be in help.
Jacob

]]> Comment on JSR-331 in different JVM languages by Pierre Schaus (@pschaus) http://cpstandard.wordpress.com/2013/04/30/jsr-331-in-different-jvm-languages/#comment-1297 Tue, 30 Apr 2013 21:13:56 +0000 http://cpstandard.wordpress.com/?p=200#comment-1297 Thanks for the link to OscaR. We should organize a competition for JVM solvers (like minizinc).

]]> Comment on JSR-331 at JavaOne 2012 by OpenRules Support http://cpstandard.wordpress.com/2012/09/29/jsr-331-at-javaone-2012/#comment-1267 Sat, 10 Nov 2012 17:09:52 +0000 http://cpstandard.wordpress.com/?p=178#comment-1267 See also this blog post http://blog.decaresystems.ie/2012/10/02/javaone-2012-day-1/

]]> Comment on JSR-331 is now an official standard! by Intellifest 2012: Jacob Feldman: Modeling and solving optimization problems « Everything Decision Management, Technically Speaking http://cpstandard.wordpress.com/2012/03/08/jsr-331-is-now-an-official-standard/#comment-1242 Thu, 25 Oct 2012 22:30:44 +0000 http://cpstandard.wordpress.com/?p=134#comment-1242 [...] decisions. Jacob has worked in this space for a long time, and has successfully pushed through JSR-331, an award winning standardization [...]

]]> Comment on JSR-331 at JavaOne 2012 by jacobfeldman http://cpstandard.wordpress.com/2012/09/29/jsr-331-at-javaone-2012/#comment-1205 Wed, 03 Oct 2012 14:28:24 +0000 http://cpstandard.wordpress.com/?p=178#comment-1205 Amel,
Java developers appreciate how “elegantly” CP API allows them to represent complex CSPs treating unknown decision variables similarly to known integers or sets, utilizing different predefined binary and global constraints and combining them using traditional O-O techniques. I warned the audience that this simplicity should not mislead them that solving small problems with the default search algorithms will automatically resolve large scale problems, for which expert knowledge may make a major impact. But CP certainly puts Java developers in a very flexible framework to address the most complex problems.

From practical experience with different CP solvers, I know that in real-world applications we always find a way to address the most complex problems that initially may look intractable. Let me disagree with your reasons for CP being “less attractive”. CP solvers (and JSR-331 too) usually cover not only a “small set of mathematical operators” but almost all major math and logical operators defined on different types of constrained objects. More importantly, you always may define your own operators. Of course, if you want to define operators/constraints on your own objects you have to implement them yourself. You can do it by simply combining the existing constraints and logical operators (see e.g. http://openrules.com/jsr331/JSR331.UserManual.pdf p.44) or by implementing completely new constraints with your own propagators. The latter capability is usually provided by a CP Solver, and JSR-331 has it too but not in the official standard (at least yet). Let me know if you want to try it and I will give you an access to an initial implementation of custom propagators.
I agree that debugging may be tricky in some cases because of the non-deterministic nature of CP. However, CP solvers usually provide you with useful “hooks” to trace and to understand what’s going on. Besides, with open source solvers you may use the standard Java debugger with your own break points.

Anyway, while general statements are usually too generic, it is always more productive to try a tool on your own problem and to address a concrete issue. If you have such issues with JSR-331, please let me know. Thanks,
Jacob

]]> Comment on JSR-331 at JavaOne 2012 by Amel Bennaceur http://cpstandard.wordpress.com/2012/09/29/jsr-331-at-javaone-2012/#comment-1204 Wed, 03 Oct 2012 11:36:51 +0000 http://cpstandard.wordpress.com/?p=178#comment-1204 Thank you very much Jacob.
I looked at the slides and the example gives the intuition but still I think (and many others do ;) that CP becomes more interesting once we have combinatorial problems and we need some efficient exploration algorithms: backtracking, branch and bound, etc.
So, I doubt any developers (even without a PhD in operation research) would do such for imbrications.
I’m doing my PhD and I’m perfectly fine with implement OP algorithms, so what motivates me to use CP is that the solution is usually “elegant” and can easily be extended. Although I find it harder to explain (in a paper for example) as the search mechanism really depends on how the solver perform the propagation, etc. and of course we may write constraints differently depending on the solver we use…
However, I think that the fact of having CP solvers implementing only a small set of mathematical operators and the lack of proper debugging mechanisms makes CP less attractive. For example, I wanted to specify constraints with ontology-based subsumption, which is a partial order relation, and had to do some coding to make it feasible in Choco. Moreover, the only way to correct a bug is by simple examples and it gets really fastidious :s while object programming languages have pretty good debugging mechanism.
Amel

]]> Comment on JSR-331 at JavaOne 2012 by Long http://cpstandard.wordpress.com/2012/09/29/jsr-331-at-javaone-2012/#comment-1203 Wed, 03 Oct 2012 04:21:03 +0000 http://cpstandard.wordpress.com/?p=178#comment-1203 I attended your session at JavaOne and thoroughly enjoy it. I can’t wait to see how I can apply to my projects.
Thanks!

]]> Comment on JSR-331 at JavaOne 2012 by jacobfeldman http://cpstandard.wordpress.com/2012/09/29/jsr-331-at-javaone-2012/#comment-1201 Tue, 02 Oct 2012 15:36:34 +0000 http://cpstandard.wordpress.com/?p=178#comment-1201 Amel,
I made my presentation yesterday at this major Java event and it seems it generated quite an interest to CP among real-world developers. I had 60+ people at my session and a very involved audience of Java developers with many good questions afterwards. Oracle plans to publish my presentation but meanwhile you may find it at http://openrules.com/pdf/CONS3255_Feldman.pdf. I demonstrated many concrete CSP samples that you may find and run yourself – see the project “org.jcp.jsr331.tck” downloadable from http://openrules.com/jsr331. Let me know if you need any assistance.
Jacob

]]> Comment on JSR-331 at JavaOne 2012 by Amel Bennaceur http://cpstandard.wordpress.com/2012/09/29/jsr-331-at-javaone-2012/#comment-1200 Tue, 02 Oct 2012 12:53:52 +0000 http://cpstandard.wordpress.com/?p=178#comment-1200 I would love to see your presentation…
I have a hard time explaining how CP works.
Most people see it as black magic and hence are suspicious…

]]> Comment on Road to CP Standardization by Six New JSR-331 Implementations with Linear Solvers | Constraint Programming Standardization Blog http://cpstandard.wordpress.com/2010/07/24/road-to-cp-standardization/#comment-1141 Thu, 26 Jul 2012 21:16:29 +0000 http://cpstandard.wordpress.com/?p=12#comment-1141 [...] we planned from the very beginning, now we’ve successfully added 6 more JSR-331 implementations using [...]

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