My Constraint Programming Blog

The SweConsNet (Network for Sweden-based researchers and practitioners of Constraint programming) Workshops are held annually in the spring. This year, SweConsNet-2014 is to be held in Kista, Sweden, June 13. Here's the call for presentations and participation:

The 13th workshop of SweConsNet, the Network for Sweden-based researchers and practitioners of Constraint programming

Hosted by:
SCALE - KTH & SICS Collaboration in Scalable Computing Systems
SICS, Electrum, Kista, Sweden
June 13th, 2014

The Network for Sweden-based researchers and practitioners of Constraint technology (SweConsNet) kindly invites you to participate in the yearly SweConsNet Workshop. The purpose of the workshop is to learn about ongoing research in Constraint Programming, existing projects and products, and further development of the network. SweConsNet Workshop 2014 is the 13th edition of this annual event.

The workshop is open to everybody interested in the theory and practice of constraint programming, whether based in Sweden or elsewhere. The scope of the workshop spans all areas of Constraint Programming, and is open to presentations and discussions addressing topics related to both theory and application.

We hope for your participation, and highly encourage you to submit a proposal for a presentation of your ongoing work, recent results, or of a relevant discussion topic. There are no paper submissions, reviews, or proceedings, hence recent conference/journal papers may also be presented.

To register, please send a brief statement of intent, and desirably the title and abstract of your talk, to Christian Schulte (cschulte at kth.se). In order to facilitate organization, please notify us of your intention to participate as soon as possible, and at the latest before May 28th, 2014. The workshop does not have a registration fee.

A preliminary list of speakers will be provided at the workshop website, and several time slots remain available.

Please forward this message to anyone who might be interested in this workshop but is not yet on the SweConsNet mailing list.

Best regards,
Christian Schulte

P.S.: If you wish to subscribe to the mailing list, please send a message to Justin Pearson (Justin.Pearson at it.uu.se).

Also, see the earlier workshops.

Posted by hakank at 09:14 AM | Permalink

The site for CP2014 (The 20th International Conference on Principles and Practice of Constraint Programming) went up (or rather: updated) the other day:

The International Conference on Principles and Practice of Constraint Programming will be in Lyon, France, from September 8th to September 12th 2014.

This will be the 20th edition of the annual conference on all aspects of computing with constraints, including: theory, algorithms, environments, languages, models and systems, applications such as decision making, resource allocation, and agreement technologies.

The site currently shows:

• Call for contributions to the CP 2014 journal track
• Call for Doctoral Program
• Call for Tutorials
• Call for Workshops
• Call for Application Papers
• Call For Technical Papers

See Dates, Calls, Submissions for more details.

Here are some placeholders for things that will be filled with contents (as of writing some are TBD'ed):

• Organization
• Venue
• Program
• Workshops

I have all intentions to attend this year as well. Last year, I blogged a bit about the conference (was actually the conference blogger, as well as co-organized the CP Solver Workshop and co-organized First International Lightning Model and Solve Competition). Also, see the official CP2013 site.

Update: This year I'm in the Application Track Committee. That will be interesting and fun.

Posted by hakank at 09:19 AM | Permalink

In his blog post After CP-2013 Jacob Feldman writes about the workshop CP Solvers: Modeling, Applications, Integration, and Standardization (CPSOLVERS). He summarizes the workshop in general and some of the discussions we had, and also mentions the CP Solver Catalog (that he initiated some months before the conference).

Jacob has a plea about the details of the discussions:

It’s hard for me to reproduce all answers and I want to invite all CPSOLVERS-2013 panelists and other CP practitioners to provide their answers as comments to this post.

I also agree with Jacob's end paragraphs:

Overall, I think the workshop has actually provided us with an industrial overview of CP products that was its main objective. We plan to get such overviews every 4 years – so I hope to see many authors of current and brand new CP tools at CPSOLVERS-2017.

P.S. I want to thank CP-2013 organizers for their constant support and a great organization of the conference.

Posted by hakank at 11:00 AM | Permalink

The presentation slides for many CP-2013 talks are now available from the Schedule page.

Posted by hakank at 07:01 PM | Permalink

After a failing publishing some of my CP-2013 photos at my Google+ page, I have now collected them all at a special page: hakank.org/constraint_programming/cp2013/pictures/. They have been collected per day,:

• 2013-09-15
• 2013-09-16
• 2013-09-17
• 2013-09-18
• 2013-09-19
• 2013-09-20

Please note:

• The photos are large and are simply scaled at the presentation page. Click on the photo to get a larger version with proper ratio.
• Many of the photos are not good but still kept since they are mementos. It's mostly because I didn't realized that using maximum zoom on my camera easily give distortions, especially with unsteady hands. Sorry about that.
• They are not labeled in any way, though they all have time stamps which might give some clues of the target.

And if you study the slides that I photographed, you get a hint in what areas of CP I'm most interested in. :-)

Posted by hakank at 07:49 PM | Permalink

Ian Gent, a member of the winning team (Mano) in the First International Lightning Model and Solve Competition this conference, has just published a blog post about how and why he and his team won: How I became one of the three "best optimizers in the world".

Ian writes very interesting details about how the team approached the problems, why they decided to solve all problems by hand, etc. I like Ian's conclusions:

What Have We Learnt For Constraint Programming?

One word. Modelling.

To expand, Modelling is hard.

To expand, we need better tools to make it easier to model constraint problems quickly. Every group should have been able to use a simple constraints tool to model the easier problems (like queens) and then get on with the other ones.

This is what I take away, and it's nice that this is research that we in St Andrews are already doing, so I hope we can push this harder after this experience.

As one of the organizers of the competition, I also thank Ian for this comments about what we can do better the next time. [This means that I have read it, but will not promise anything. :-)]

Also, see my summary of the competition: CP-2013: The Conference Day 3 (Thursday) and CP-2013: Competition problems, rules, and instances.

Posted by hakank at 09:11 PM | Permalink

Friday, Day 4 (last day

After yesterday's quite hectic agenda, today was was - for me at least - a much more relaxed day. Though the organizers and the organge guys was busy to the last minute.

First, I would like to thank all the organizers and the "volunteers" [the quotes was official] for a really well organized and interesting conference. It was my first CP-conference so I didn't really know what to expect, but it was just fun being there, both for the talks but also to meet and discuss CP with the leading experts in the field (or just listening to their discussions).

So, the day was fun and started with the invited talk by Torsten Schaub on ASP (Answer Set Programming), which is a paradigm different from CP in details but quite close in goals and some principles. The system mentioned was Potassco. You can see more about it at my Answer Set Programming page.

After Torsten's talk was the Modeling track with very interesting talks, and I especially liked the CP systems talks : Ozgur Akgun talked about Automated Symmetry Breaking and Model Selection in Conjure. More about Conjure is here.

After that Daniel Fontaine talked about "Model Combinatorics for Hybrid Optimization" in Objective-CP (sorry there is no link to Objective-CP yet) and then Kevin Leo about "Globalizing Constraint Models", a project which tries to automatically make more efficient MiniZinc models.

The tutorial by Phil Kilby about CP for Vehicle Routing Problems was very inspiring. He explained a general CP model which can solve many of the different VRP problems. Really interesting and important stuff.

Last session for the day, and the conference, was "Global Constraints and Conflicts" with four talks which - I have to admit - sometimes was a bit over my head. Though I think that the results they showed was quite impressive.

And the conference is now all. Again, thanks for organizing this! And thanks to all wonderful, inspiring, and bright people in the CP world.

This is last daily report blog post as the CP-2013's official blogger. Hope you have enjoyed it as much as I when writing it; blogging is a great way to digest things. Feel free to contact me in CP related matters: hakank@gmail.com.

Oh, I almost forgot today's first greetings with e-contacts (with a slightly extended meaning of e-contacts): Torsten Schaub, Toby Walsh, Christopher Mears, Roland Yap, Thibaut Feydy.

Posted by hakank at 12:29 AM | Permalink

Here are the CP-2013 competition problems (with some small corrections by Peter Stuckey): cp2013_competition_20130919.pdf. The rules might also be interesting to read to see the conditions of the competition: cp2013_competition_rules_20130919.pdf. The problem instances are here: cp2013_competition_instances_20130919.zip and are named as "problem_instance.dzn", where instance 0 is the instance that's shown in the problem documentation.

If you have a nice model (in CP or some other paradigm) that solves the competition instances on any of the problems, feel free to mail me at hakank@gmail.com. If I got more than a few models/programs, I might put them on a web page.

Have fun!

Update 2013-09-24: The problem document, the rules, and the instances has now been added to the competition page. Thanks, Guido.

Posted by hakank at 11:20 PM | Permalink

Thursday, Day 3

Today was an exciting and hectic day. It started with Pascal Van Hentenryck and Laurent Michel presented Objective-CP, a CP system (in progress) built in Objective-C. It looked very versatile and flexible so it will be really fun testing it, even though I haven't written a single line of code in Objective-C. (Right after I read the paper I ordered a book in Objective-C just to be prepared.)

One other talk I enjoyed very much today was Tias Guns ACP Doctoral Research Award talk: "Declarative Pattering Mining Using Constraint Programming". The system he built is CP4IM (which I tested some year ago and it's impressive work).

I have to admit that I skipped some of the other talks since I was preparing (both mentally and technically) for the penultimate event of the day, namely:

The hectic part of the day was the competition (formally: First International Lightning Model and Solve Competition), since I was one of the organizers, together with Peter Stuckey and with a huge amount of technical/practical help by Farshid Hassani Bijarbooneh. Peter wrote the problems and the checkers for the problems and I wrote the framework for reading the submission files (in MiniZinc data format, .dzn) to be fed into Peter's checkers. (I also wrote code for detecting if any of the teams should trying to "beat the system" in certain ways, but all the teams behaved very honourably).

It was a fun competition, although perhaps a bit too hard problems. Later on - I'm not sure when hopefully this Friday or Saturday - we will publish the problems somewhere so anyone can see what the teams was exposed to. I will of course then blog about it. Later: And here are the problems (with some corrections by Peter): cp2013_competition_20130919.pdf (PDF). I also think that the rules can be interesting to read: cp2013_competition_rules_20130919.pdf.

Here is the table of the teams that got at least one point, i.e. submitted at least one correct solution. There where four teams - not mentioned below - that didn't got any points. In all there where 10 competing teams.

Id	Team	Points	Team members	Medal
7	Mano	71 (Competition winner! )	Allan Van Gelder, Ian Gent, Ian Miguel	Gold
4	Be Cool and Friends	57	Pierre Schaus, Renauld Hartert, Jean-Noël Monette	Silver
8	CO4	47	Valentin Mayer-Eichberger, Johannes Waldemann, Sebastian Will	Bronze
1	Lazy Guy	39	Andreas Schutt, Thibault Feydy, Geoffrey Chu	-
5	Monash	26	Kevin Leo, Guido Tack, Christopher Mears	-
10	Other	6	Gabriel Hjort Blinell, Roberto Castañeda Lozano, Mohammed Siala	-

Congratulations to the medallists! And especially to the winners: team Mano, who - interestingly enough - solved the problems only by hand (as indicated by their team name).

And thanks to all the other teams that attended the competition!

After the competition it was a very pleasant Banquet Dinner, with lots of interesting discussions as well as both formal and not so formal speeches.

Handshakes (with the people I've had just e-contacts with before) : Andreas Schutt, David Rijsman, Ian Miguel.

Tomorrow, I'm especially looking forward to the invited talk about ASP by Torsten Schaub. (I tested ASP somewhat some year ago: see My ASP page; it's quite fun to model in ASP, different and fun.). Another talk that will be interesting is Ozgur Akgun who will talk about "Automated Symmetry Breaking and Model Selection in Conjure".

Posted by hakank at 11:55 PM | Permalink

Wednesday, Day 2

Today started and ended with two very inspiring talks, both showing how to use optimization for important issues, and both also showed the need for multi-disciplicary approaches for these kind of projects, i.e. not only CP or optimization in general but also machine learning, simulation, agent-based modeling (all areas in which I've been interested in on and off, especially machine learning/data mining).

Michaela Milano started the day with the invited talk Optimization for Policy Making: the Cornerstone for an Integrated Approach where the general goal is to build a policy making system (decision support) for energy consumption.

The last lecture was Pascal Van Hentenryck's exiting public lecture Decide Different! about many projects he and his collegues at NICTA (Australia) and other universities was involved in, such as disaster recovery. He also showed two interesting example of optimization in crowd funding and similar systems.

A related aside: Pascal is also behind the very interesting Coursera online Course Discrete Optimization. I have not yet seen all the lectures, but the one about Dynamic Programming and Constraint Programming was excellent, especially for introducing CP. (I will later see the rest of the course, Local search and Integer programming, and perhap be more serious and do some of the homeworks). [In his wonderful introduction lecture, Pascal showed Kidney Exchange as an example of a hard discrete optimization, and that inspired me to write a small MiniZinc model to solve these kind of problems, though it cannot at all handle the huge number of people that is required: about 80000 people is of a need of a kidney. My model solves a problem with 500 people (randomly generated) fairly simple, and 1000 with some more sweat.]

Some other interesting talks today: In the Search track Geoffrey Chu talked about "Dominance Driven Search" (yet another approach that might lead us to a powerful black box solving?), and Marc Shoenauer talked about Bandit-based Search for CP (which - to be honest - was more interesting than I first anticipated). Jean-Charles Régin's talk about Embarrassingly Parallel Search showed a way which seems to be a good way to do massive parallel search (though I'm definitely not an expert in this area).

Ian Gent and Lars Kotthoff held a kind of iconoclastic tutorial about recomputation, which may very well be the future way of doing repeatable experiments in computer science (and surely in other disciplines that use computer experiments). It seems to be quite easy both to submit an experiment to the site and especially to install and redo the experiment. See http://www.recomputation.org/ for more information. The tag line for the blog/project is If we can compute your experiment now, anyone can recompute it 20 years from now. Six of the accepted papers has their experiment at Recomputation.org, see here. For a simple demo experiment, see Our First Experiment: A Chess Puzzle.

My favorite talk from the Global Constraint track was "Solving String Constraints: The Case for Constraint Programming", where Pierre Flener presented the paper by Jun He et.al. The paper compared a CP approach with dedicated solver such as Hampi, Kaluza and Sushi for certain string constraint benchmark. The CP solver dominated these solvers completely. (I actually played with Hampi this summer missed much of the things I'm used to with a CP solver.)

Tomorrow (Thursday) will be interesting. It starts with a presentation of a new CP system: Objective-CP (a CP solver written in Objective-C) and ends with the First International Lightning Model and Solve Competition . I'm also looking forward to Tias Guns' ACP Doctoral Research Award: "Declarative Pattern Mining using Constraint Programming". Oh, sorry. The day actually ends with the Conference Banquet.

(Greeting list today: Barry Hurley, Geoffrey Chu, Laurent Michel.)

Posted by hakank at 09:31 PM | Permalink

Here are some of my CP-2013 photos so far (Google+ album), taken from my POV.

[Later: I've got some complaints that the link to the photos don't work. Sorry about that. Perhaps it's required that one is a Google+ user to look at the album? I will post these at my site, but that will be after the conference.]

Even later: See CP2013: Photos from the conference for links to the photos.

Posted by hakank at 06:40 AM | Permalink

Tuesday, September 17

This is the first "real" day of the Conference. Yesterday, the workshop and doctoral program day, was the zeroth day.

Let me first say I'm sorry that I mislead you yesterday. The talks by Jun He and Pascal are not until tomorrow, Wednesday. That blog post is changed now. Also, it should probably be called "Day 0" but changing that would destroy the links.

And as of this morning, I'm the official offical conference blogger (yesterday I was only the inofficial official conference blogger). As you've already seen it's not about everything at the conference, just a report of what I happen to like or have noticed - as always on my blogs.

Here are some highlights from today.

These following two talks by Peter Stuckey I've really looked forward to:

First Peter's Invited talk "Those who forget the past are condemned to repeat it." The final words was "The Search is Dead. Long Live Proof". A very interesting and provocative talk; and the research is very interesting too, of course. It will very interesting to following this. As a modeler it would be nice with this as ground for a black box solver (at least in my dreams).

And then his report about MiniZinc challenge 2013 results. Here's the medals:

Medal	Fixed	Free	Par	Open
GOLD	opturion	opturion	or-tools	or-tools
SILVER	or-tools	or-tool	choco	choco
BRONZE	gecode	iz_plus	opturion	opturion

Congratulations to all!!

This year Opturion CPX and or-tools did really well. As Peter said: The king [Gecode] is dead, Long Live the King. Gecode finally knocked of its perch of winning ALL previous gold medals.

As in later years, the chuffed solver was actually the best solver in both fixed and free category but since it's a G12 solver it can't get any official place. However, or-tools was better than chuffed in the parallel class (and open) this year (with chuffed as second).

If you wonder how the FlatZinc solver by Neng-Fa Zhou and me (the Picat solver) did, it came last in all categories, which was not especially surprising for me; I'm glad we got some points. We'll try to do better the next year (and this is - as Peter mentioned - one of the purposes of the challenge).

Here is the URL from Peter's talk to the result page: http://www.minizinc.org/challenge2013/results2013.html [later: this link works now.]

Related: MiniZinc Challenge Medals 2008-2012

Peter also mentioned the competition at this conference : Lightning Model and Solve competition. The registration form is at the boards. After just some hours there where already about 10 registered. That's great!

Before lunch there was also the three Best Papers talks. All was perhaps not in my forte but really worthwhile listening to.

After the lunch, I went strictly to the left column in the program: first the Applications track, and then the Bin Packing track. One of my two favorite talks where Helmut Simonis' talk about an application of Model Seeker (the last year I blogged about it in Beldiceanu and Simonis: A Model Seeker). The other talk was Andrea Rendl's about Balancing Bike Balancing System. I like these kind of practical applications (and which are not very hard to understand.)

It was interesting to learn that CP was used to calculate orbits in chaotic systems; a long time ago I read some popular science books - as well as some not-so-popular books - about this, and played with quite a few chaos systems

(I didn't attend the ACP General Assembly.)

The scheduled day ended with a reception drink at Östgöta nation. I hope everyone else had lovely discussions and made new contacts.

Assorted things

I was asked about notes from the panel discussion at CP Solver workshop yesterday. Unfortunately we didn't take any notes, but I hope to collect the highlights later this week.

Today's people greet (i.e. the one I've only e-communicated with before and today at least shaked hands with): Narendra Jussien, Barry O'Sullivan, Andrea Rendl, Peter Nightingale. There are still some left to greet. I also made some new friends, and this is actually one of the reason I'm attending this conference. It was mostly CP solver guys and should be to no surprise to the followers of this blog.

Finally, for you you who don't know me earlier: I'm the guy that sometimes wearing an eye patch. Please don't worry, it's just because I don't have a lens in my left eye after an unsuccessful cataract operation this May, and sometimes too much light tend to confuse my small brain. Eventually this will be fixed with a special contact lens.

Posted by hakank at 10:54 PM | Permalink

Today was the first day [later: zeroth day] of the CP-2013 conference: The Doctorial program and Workshops day.

The venue, Uppsala University main building, is a very old (the oldest in Scandinavia, from late 15th century of so) and is beautiful and very impressive (though the quarter bell should perhaps be fixed since it's off by some minutes).

When we arrived at the morning, we met a lot of CP guys with wonderful orange T-shirts (designed by Joseph Scott) which indicate the tech and handy persons, those who do everything behind the scenes, i.e. just makes everything work. This is much appreciated!

As mentioned earlier, I was co-organizing the CP Solver workshop (the presentations are available via the link), and did also a talk (CP Solvers/Learning Constraint Programming), and was also responsible for the "5 minutes left" warning messages (a much helpful feature for the talkers I guess) so I didn't attend other workshops (from what I heard they where great as well).

Our workshop was quite well visited (perhaps in part because almost all speakers was in the audience but there are of course many non-talkers in the audience). I liked the mix of the talks: commercial systems and open source systems, old system and newer systems, and all talkers have some point of view that was interesting. The workshop ended with a hour long Panel Discussion - moderated by Hemut Simonis - with many interesting general discussions about the role and future(s) of CP solvers.

And from a personal point, it was really great to be able to at least greet to some I've only had electronic communication with earlier: Jacob Feldman, Chris Kuip, Victor Zverovich, Peter Stuckey, Pascal Van Hentenryck, Toshimitsu Fujiwara, Jean-Guillaume Fages, Guido Tack, Pierre Schaus.

The (scheduled) day ended with with a "Welcome drink" in the Chancellor room with a lot of old portrait painting (what I understood, this is one of the largest collection in Scandinavia). In all this first day was attended by about 100, about half of the total.

Tomorrow (Tuesday) is the first "real" conference day. Some of the talks I'm looking forward to are:

• Peter J. Stuckey's Invited talk: "Those Who Cannot Remember the Past are Condemned to Repeat it"
• Peter J, Stuckey: "MiniZinc Challenge results"
• Jun He, et.al: "Solving String Constraints: The Case for Constraint Programming" [later: sorry, wrong day]
• Pascal Van Hentenryck Invited Public Lecture: "Decide Different" [later: sorry, wrong day]

Posted by hakank at 09:43 PM | Permalink

In a few days it's time for CP-2013 (The 19th International Conference on Principles and Practice of Constraint Programming), in Uppsala, Sweden.

During the conference, I will:

• blog (at this blog)
• tweet, at hakankj, using the tag #cp2013 (not all the hits are about the real CP-2013 conference though). Some tweets will probably also be tagged with #copr.
• and perhaps also at Google+

I don't know when, how often or how much this reporting will be. It will be just from my own perspective and not a full report on every talk. Hopefully it will convey that I have looked forward to this conference a long time, both listening to the talk (of course), and also to finally meet all the great guys I've just have had mail contact with - or just read about - since I started to be interested in constraint programming (in 2008).

I'm quite sure there will be other that blog/tweet/etc about and during the conference.

Some especially interesting things that I'm looking forward to (for miscellaneous reasons):

• The workshop I will attend (and am a co-organizer of): CP Solvers: Modeling, Applications, Integration, and Standardization. Unfortunately this means that I miss the the other interesting workshops
• The Invited talks (especially the presentation of The Objective­CP Optimization System by Pascal Van Hentenryck and Laurent Michel.)
• MiniZinc Challenge Result. The MiniZinc challenges are always interesting to follow. This year Neng-Fa Zhou and I have submitted the Picat FlatZinc solver, so it will be extra exciting. Here is the result of the earlier MiniZinc challenges (2008-2012).
• First International Lightning Model and Solve Competition, organized by Peter J. Stuckey, myself and with greatly appreciated technical support by Farshid Hassani Bijarbooneh.

This will be a fun week!

Here are some useful links:

• CP-2013
• Schedule
• University floorplans
• Local information, venue

Posted by hakank at 12:41 PM | Permalink

Just a short notice that the early registration of CP 2013 (Uppsala, Sweden) has a deadline very soon: 8 August. The not so early registration is a month away...

From the Call for Participation:

CP 2013 Nineteenth International Conference on Principles and Practice of Constraint Programming Uppsala, Sweden September 16-20, 2013

Also, see the full conference program.

Posted by hakank at 05:55 PM | Permalink

The Workshops for CP-2013 (Uppsala, 16 September 2013) has been published. From the Workshops page:

The following workshops will take place before the main conference on September 16.

WCB13: Constraint Based Methods for Bioinformatics

WCB'13 is the 9-th of a series of consecutive Workshop on Constraint Based Methods for Bioinformatics. The topics of interest are all those concerning bioinformatics and constraints and related techniques.
workshop homepage

TRICS13: Techniques foR Implementing Constraint programming Systems

Constraint programming systems are software systems that support the modeling and solving of problems using constraint programming. Such systems include constraint programming libraries and runtime systems for constraint programming languages. This workshop, the fourth in the series, will focus on implementation issues of such systems.
workshop homepage

CSP-SAT: 3rd International Workshop on the Cross-Fertilization between CSP and SAT

Constraint Satisfaction Problems (CSP’s) and Boolean Satisfiability Problems (SAT) have much in common. However, they also differ in many important aspects, which result in major differences in solution techniques. This workshop is designed as a venue for bridging the gap and for cross-fertilization between the two communities.

CP Solvers: Modeling, Applications, Integration, and Standardization

The objective of this workshop is to get an industrial overview of currently available CP solvers and their use in real-world applications. The focus of the workshop will be not on implementation but rather on modeling, applications, integration, and standardization. Such an overview will fill a gap in the program of recent CP conferences and will allow CP developers and researchers to share the most recent experience of the actual use of different CP-based tools.
workshop homepage

Workshop on Optimization for Smart Cities

Policy makers who run the complex network of diverse people, expected services and aging infrastructure are on a constant search for more efficient ways to analyse data, anticipate problems and coordinate resources in their cities. This workshop has the purpose of bringing together scholars and practitioners that work on the solution of problems related to the improvement of the quality of life and the use of resources in cities, to make cities smarter.
workshop homepage

COSpeL: Domain Specific Languages in Combinatorial Optimization

Domain Specific Languages (DSLs) are programming languages or libraries developed to handle specific tasks. The aim of COSpeL is to bring together people interested in the development and use of DSLs in the context of combinatorial optimization.
workshop homepage

ModRef: Constraint Modelling and Reformulation

This workshop covers modelling and reformulation techniques that make constraint programming more accessible and easier to use, widening the use of CP technology.
workshop homepage

As mentioned earlier, I have a special interest in the CP Solvers: Modeling, Applications, Integration, and Standardization Workshop

Posted by hakank at 08:30 PM | Permalink

An addendum to CP-2013 Workshop "CP Solvers: Modeling, Applications, Integration, and Standardization" (Uppsala, Sweden):

If you an author of a CP solver, we ask you to fill out the following questionnaire (even if you do not plan to submit a presentation or attend the workshop). We plan to present a summary of all CP Solvers at this website before the start of the conference.

And here is the link to the workshop page: Workshop "CP Solvers: Modeling, Applications, Integration, and Standardization".

Posted by hakank at 07:14 AM | Permalink

I'm very happy to announce the CP-2013 Workshop "CP Solvers: Modeling, Applications, Integration, and Standardization":

To be held at the 19th International Conference on the Principles and Practice of Constraint Programming (http://cp2013.a4cp.org/) in Uppsala, Sweden on Monday September 16, 2013.

Objectives and Scope
The objective of this workshop is to get an industrial overview of currently available CP solvers and their use in real-world applications. The focus of the workshop will be not on implementation but rather on modeling, applications, integration, and standardization. Such an overview will fill a gap in the program of recent CP conferences and will allow CP developers and researchers to share the most recent experience of the actual use of different CP-based tools.

We invite authors of all commercial and open source CP solvers to submit their presentations that should include (but not be limited to) the following topics:

• Demonstration of modeling facilities using a commonly known problem from the CSPLib
• Implementation programming languages and why they were selected
• Covered variable types, global constraints, and search algorithms
• Integration with LP/MIP/SAT tools
• Integration with business rules, predictive analytics, and other decision making techniques
• Real-world use: positive and negative experience
• Standardization and future plans

If you an author of a CP solver, we ask you to fill out the following questionnaire (even if you do not plan to submit a presentation or attend the workshop). We plan to present a summary of all CP Solvers at this website before the start of the conference.

We also welcome application developers and researchers who use different CP tools and who are willing to share their practical experience.

A special focus will be on CP standardization efforts including:

• Development of CP APIs for different programming environments
• CP XML for interchange of constraint satisfaction/optimization problems
• CP design patterns
• Libraries of commonly used constraints
• Collections of constraint satisfaction and optimization problems.

An expert panel discussion will be held at the end of this one-day workshop.

We hope that the workshop will help to improve communication between different CP vendors, between solver developers and their users, and will ultimately encourage a wider use of CP technology as a key component of the modern decision making applications.

Target Audience

• Developers and users of different CP solvers
• Business application developers who want to incorporate CP-based tools into their decision support systems
• CP researchers.

Schedule
[To be defined]

Important Dates

• Sunday, June 16 Presentation title and abstract submission
• Tuesday, July 16 Acceptance notification
• Friday, August 16 Complete presentation submission
• Monday, September 16 Workshop

Organizing Committee

• Jacob Feldman, OpenRules, Monroe, NJ, USA jacobfeldman@openrules.com
• Helmut Simonis, 4C, Cork, Ireland h.simonis@4c.ucc.ie
• Hakan Kjellerstrand, Independent Researcher, Malmo, Sweden hakank@gmail.com

Submission
All abstracts and presentations must be submitted in PDF format using EasyChair. All accepted presentations will be made publicly available of the workshop’s website. At least one author of any accepted presentation must attend the event. An accepted presentation will be withdrawn if no such participation is secured with the payment of the workshop dues.

Please note that we invite authors of all CP solvers written using any languages to make brief presentations of their tools.

This is exciting, not only for the workshop itself (which is about my favorite areas in CP), but also because I'm a co-organizer (an honourable task). This will be very interesting. I hope to see you there!

Posted by hakank at 09:27 PM | Permalink