Dear Christian, > Co-incidence: I have been adding a naïve (but better than the decomposition) > version of the constraint to Gecode recently. I will move that code to the > trunk this week (there are still some glitches to fix before that).
now that's convenient! On which algorithm is it based? > The plan is to eventually improve to a state-of-the-art implementation. This sounds good. Would you consider the sweep algorithm proposed by Beldiceanu and Carlsson as state-of-the-art, or are there any alternatives? Btw do you know which one is applied in JaCoP? > Taking code directly from Jacop into Gecode will not work due to their > license. The intention was more to get an inspiration. Anyway, both frameworks probably differ too much. > Maybe you would even be interested to contribute? At least you > would have a nice structure to start from. Yes, we can indeed think about this. Though I am not yet in a state where I can "hack" something into Gecode, it would be a good opportunity to start doing so. Best regards, Sandro > We will release soonish a new version that will incorporate that but there > are more things to be done before a release. > > Best > Christian > > -- > Christian Schulte, KTH, web.it.kth.se/~cschulte/ > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf > Of Sandro Pirkwieser > Sent: Wednesday, May 25, 2011 9:01 PM > To: [email protected] > Subject: [gecode-users] diffn constraint for Gecode > > Hello, > > I'm using Gecode to tackle a 2D packing subproblem inside an optimization > problem. The subproblem is about packing rectangles (for the meantime > without rotation) into a given larger rectangle and many instances of > moderate size need to be solved. Fortunately I was able to start with the > perfect-square example, where the adapted variant already performs quite > good (using the cumulatives constraint). Also enabling branching on > intervals yielded a speed-up. Now I was wondering if someone of you already > implemented a suitable diffn constraint (see > http://www.emn.fr/z-info/sdemasse/gccat/Cdiffn.html) in Gecode. In this way > the non-overlapping part would (presumably) be tackled more efficiently and > give an additional performance boost. Do you think having a look at the > diff/diff2 implementation in JaCoP is useful for implementing it in Gecode? > Thanks! > > Best regards, > Sandro > > _______________________________________________ > Gecode users mailing list > [email protected] > https://www.gecode.org/mailman/listinfo/gecode-users > _______________________________________________ Gecode users mailing list [email protected] https://www.gecode.org/mailman/listinfo/gecode-users
