Hi Felix, I have been thinking about your idea and I very much like it.
How about the following generalization: one can pass to a brancher a filter function (that is, a member function of the space). If a filter function is passed it is used for selecting variables for branching: only if the filter function returns true for a variable, the variable is considered for normal selection. The function can be passed through the normal options for branching (VarBranch) that is also used for tie breaking and randomized selection. Would that make sense? It is less general than what Guido proposed but easily available to the average modeler. I thought about it a little and I know how to efficiently implement it. Cheers Christian -- Christian Schulte, www.ict.kth.se/~cschulte/ -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Felix Brandt Sent: Saturday, August 28, 2010 9:52 AM To: [email protected] Subject: [gecode-users] Idea for extending ViewBrancher Hi, for a recent project I wrote a custom brancher (similar to the ViewBrancher) that only branches variables within a certain interval. The variables, which do not intersect the interval, are considered as if they are already assigned. In my case I wasn't interested in the values if they did not match the given interval, but also did not want to add auxiliary variables and constraints to be able to use standard branchers. Furthermore, I could not just assign border values without breaking constraints. I assume that such a brancher can also be advantageous in other setups, where one wants to apply varying branching strategies to different parts of the variable domains. If this idea is of interest for the project, I could try to extend the current ViewValueBrancher. Right now, I'm not sure where to start. Probably adapting ViewBrancher<ViewSel>::status(const Space&) is a good starting point, but it's quite deep in the object hierarchy so I assume it's not *that* easy. Additionally, inheriting from ViewBrancher seems to produce a lot of duplicated code (for brancher assembly and strategy selection). Any suggestions? Regards, Felix PS: If I miss something obvious or this feature is already present, I would appreciate any hint :-) _______________________________________________ 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
