Hi Martin, Please try the sketch that should work just fine and that's what I meant in the first place...
Christian -- Christian Schulte, www.ict.kth.se/~cschulte/ -----Original Message----- From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On Behalf Of Martin Mann Sent: Tuesday, January 29, 2013 12:08 PM To: Guido Tack Cc: gecode user list Subject: Re: [gecode-users] splitting branching in full enumeration and first-fail check Hi Guido, mhh... that was my gut feeling when reading the assign documentation. So it basically does not really do a search for solutions but just assigns the (first) variable, does propagation, continues with the remaining variables until all are assign or no solution is found... no, that's not what I need. True enough. So either I do the external handling as Christian suggested, ie. something like ////////////////////////////////////// CSP p = new CSP(); // branch on A branch(p, p.A, INT_VAR_SIZE_MIN, INT_VAL_MIN); Gecode::DFS<CSP> dfsA(p); delete p; // get all solutions for valid A assignments while ( CSP solA = dfsA.next() ) { // branch on B branch( solA, solA.B, INT_VAR_SIZE_MIN, INT_VAL_MIN); Gecode::DFS<CSP> dfsB(solA); // get first solution for B assignment if( CSP solAB = dfsB.next() ) { cout <<"overall solution = " <<solAB <<endl; delete solAB; } delete solA; } ////////////////////////////////////// or I am back to my first guess, ie. I have to write my own branching that stops after the first solution on B to fall back to the branching on A... :/ what a pitty. :) Was hopeing on something hidden in the space (as the branching) without much work. But thanks for your thoughts. Helped a lot to clearify the problem. So long, Martin Am 28.01.2013 22:55, schrieb Guido Tack: > Hi guys, > > just using assign after branching on A doesn't work. Assign has a very different semantics, you can only use it if you are guaranteed to find a solution using the leftmost branch. > What you need here is either the two-stage search Christian mentioned: for every solution to A, run a new search engine that finds a single solution for the rest of the variables. Or implement something like the "once" combinator. I think our radiotherapy example includes code for this. > We can't provide a generic solution very easily, because it's a combinator that modifies another search heuristic (so it would have to be "wrapped around" the existing branchers). > > Cheers, > Guido > _______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users _______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
