[gecode-users] implementing branching heuristics

[Christian Schulte]

Yes, using a search engine should point always to the freshest version. It
is highly annoying if you get zillions of webpages all of which are out of
date (for example, Java and many other software packages require (or ask
for) the same).

Gecode is _not_ GPL, it is distributed under the MIT license (check the
license, please)! And we kindly ask. So if you want to make the life of
other users more miserable, than you are still allowed to do so ;-) However,
we just ask for common sense here.

I am unfamiliar which tag to set to not have stuff indexed, I am only
familiar with having a robots.txt file when using apache.

Cheers
Christian

--
Christian Schulte, www.ict.kth.se/~cschulte/

-----Original Message-----
From: Oliver Kullmann [mailto:O.Kullmann at swansea.ac.uk] 
Sent: Monday, June 09, 2008 9:32 PM
To: Christian Schulte; users at gecode.org
Subject: Re: [gecode-users] implementing branching heuristics

thanks for the information!

I'll have a look into the examples, and see whether I
can hack them.

Oliver

P.S. Regarding the documentation one finds the statement:

"We kindly ask that documentation is not installed anywhere in such a way
that it will be indexed by search engines."

I wonder what is the reason for this? Actually, it creates a problem
for my system, since the complete documentation is mirrored on the
Internet, and I make available also all documentation of external
sources installed by the OKlibrary, and this should include Gecode.
Would it be enough if on the main page which links to the documentation
I set the meta-tags to "no search engines"?

Isn't the documentation also open-source?
Perhaps your reason is that search-engines shall point to
your site, not to others?
But this seems not compatible to me to the GPL licence, which
doesn't allow to put restrictions on further distribution?



On Sun, Jun 08, 2008 at 01:10:05PM +0200, Christian Schulte wrote:
> Hi,
> 
> please have a look at some of the examples that come with Gecode, there
you
> find how branch (which in turn creates simple variable/value branchings)
is
> used with different heuristics. There are two examples (black-hole.cc and
> queen-armies.cc) that have simple custom branchings which might give you
> some additional hints.
> 
> The current trunk has more support for predefined branchings (randomized,
> tie-breaking, etc) that should make it into Gecode 3.* (scheduled to be
> released around Sep/Oct). 
> 
> All the best
> Christian
> 
> --
> Christian Schulte, www.ict.kth.se/~cschulte/
> 
> 
> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
> Of Oliver Kullmann
> Sent: Friday, June 06, 2008 9:55 PM
> To: users at gecode.org
> Subject: [gecode-users] implementing branching heuristics
> 
> Hello,
> 
> based on my general theory of branching heuristics,
> I would like to take some standard backtracking CSP solvers,
> where I can just replace the variable ordering heuristics
> (responsible for choosing the branching variable),
> and there I would like to plug-in my generic
> heuristics instead --- I expect relevant
> performance gains.
> 
> The whole theory has been developed in the context
> of SAT, but it is applicable for any width of
> branchings (not just binary branchings), and this
> is actually one of its strengths.
> 
> If somebody wants to read about it, please have
> a look at report #7 at
> 
> http://www.swan.ac.uk/compsci/research/reports/2008/index.html 
> 
> It should be fairly easy to apply my generic heuristics.
> I looked a bit at Minion, but this looks too much
> black-box to me.
> 
> I guess in principle with gecode it should be doable.
> But the documentation is rather terse, and I also
> couldn't find some standard solvers, where I just
> would replace some functions regarding the heuristics.
> 
> Perhaps somebody can help me here?
> Or, if somebody is interested, we could have a collaboration.
> I actually expect a "quick victory", i.e., it should
> be quickly implementable, and it should yield some
> nice improvements under fairly general circumstances.
> 
> So, I hope somebody is interest in a 
> quick paper which will revolutionise CSP ;-)
> Actually, I think it will be interesting.
> 
> Oliver
> 
> P.S. Another field for possible collaboration
> would be library development: I am developing
> the OKlibrary (http://www.ok-sat-library.org),
> a generative library for generalised SAT solving.
> In principle the OKlibrary covers also CSP,
> but I'm yet "pre-alpha" :-(.
> 
> P.S.P.S. I noticed in the documentation
> of gecode that "branchings" etc. are
> used in a from my point of view somewhat
> non-standard sense. I'm using "branching"
> etc. as used by the SAT community and as
> explained in my article, but this seems to
> me also compatible to the notions used
> in the Handbook of Constraint Satisfaction.
> 
> -- 
> Dr. Oliver Kullmann
> Computer Science Department
> Swansea University
> Faraday Building, Singleton Park
> Swansea SA2 8PP, UK
> http://cs.swan.ac.uk/~csoliver/
> 
> _______________________________________________
> Gecode users mailing list
> users at gecode.org
> https://www.gecode.org/mailman/listinfo/gecode-users

-- 
Dr. Oliver Kullmann
Computer Science Department
Swansea University
Faraday Building, Singleton Park
Swansea SA2 8PP, UK
http://cs.swan.ac.uk/~csoliver/