Hi everybody, thanks to your answers Mikael and the silent support and mails from Daniel Przybilla I have a better understanding of the Advisors, their use and functionality.
Now the question appears: is the effort/overhead worth for me or not? I had a look at Mikaels thesis and the final statement that Advisors are mainly advantageous for n-ary constraint and not that useful for e.g. binary constraints (correct me if I got it wrong). Thus, I would like to get your feeling on my constraint, because you are the experts on your system! ;) ================ My problem: ================ I have a binary constraint propagator p(X,Y) that does a very strong but expensive filtering on the domains of variables X and Y. Thus I would like to delay the application until one of the domain sizes is smaller than a certain threshold. In Gecode 1.3.* I managed like that: - I subscribed the propagator for domain changes on the two variables - within the propagate function I checked if the minimal domain size of both is smaller than my threshold - if so I ran the filtering algorithm, otherwise I returned that nothing could be propagated (I was lazy and know this is kind of a hack.. ;) ) In my Gecode 3.* reimplementation I want to do it in the best way possible. So the question is: Do I stick to the old "hack" or is it worth a look to implement Advisors that do the domain size check for me? ================================= The CSP itself is quite simple: ================================= - n variables : X_i with 1 <= i <= n - one alldiff : distinct( X_1,..,X_n ) - (n-1) binary constraints : p(X_i, X_(i+1)) with 1 <= i < n (for anybody even more interested in details : p encodes a neighboring constraint in a lattice and the whole CSP encodes a self-avoiding-walk of length n on a lattice) ================================= Soo... the again final question: *Is it worth to use an Advisor for my domain size check? Or is the hack nasty but most probably faster?* I know it is hard for you to give a statement without knowledge on the propagator's details but an expert guess would be sufficient for me. ;) Thanks a lot! Martin -- Martin Mann, Dipl. Bioinf. Bioinformatics - Inst. of Computer Science Albert-Ludwigs-University Freiburg Tel: ++49-761-203-8259 Fax: ++49-761-203-7462 http://www.bioinf.uni-freiburg.de/~mmann/ _______________________________________________ Gecode users mailing list us...@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
