Hi Kish, You are right. A propagator in Gecode is required to become entailed (or failed) if all of its variables are assigned.
Cheers Christian -- Christian Schulte, www.gecode.org/~schulte Professor of Computer Science, KTH, cschu...@kth.se Expert Researcher, SICS, cschu...@sics.se -----Original Message----- From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On Behalf Of Kish Shen Sent: Tuesday, June 30, 2015 5:02 PM To: users@gecode.org Subject: Re: [gecode-users] finding number of propagators for s Space, relation to floundering Hi Christian, Thanks for your reply. I wasn't really thinking that there was a bug, but rather if still having propagators around after you program finishes is a good indicator that there might be problems. For example, there may be some good reasons why propagators may remain after they are entailed in Gecode, as with the argmin case. I did wonder if it was worthwhile to detect the situation I found and remove the propagator (assuming it is not wrong to do so, which your reply suggest it is not wrong). Do propagators always disappear when their variables all have a singleton domain? I was trying constraints where variables still have more than one domain value after they are entailed because in gfd I can't get the degree of a variable that are not bound (i.e. have more than one value in its domain). Cheers, Kish On 30/06/2015 10:56, Christian Schulte wrote: > There is no guarantee that propagators detect entailment perfectly! > So, no bug. > > A space has a function propagators() that returns the number of > propagators in a space. > > Cheers > Christian > > -- > Christian Schulte, www.gecode.org/~schulte Professor of Computer > Science, KTH, cschu...@kth.se Expert Researcher, SICS, > cschu...@sics.se > > > -----Original Message----- > From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On > Behalf Of Kish Shen > Sent: Tuesday, June 30, 2015 5:15 AM > To: users@gecode.org > Subject: Re: [gecode-users] finding number of propagators for s Space, > relation to floundering > > On 29/06/2015 23:51, Kish Shen wrote: >> >> ?- A :: 1 .. 20, gfd : min([100, A], M), get_constraints_number(M, D). >> >> This shows that the variable M (and I also checked A, not shown here) >> still have a propagator attached to it > > Thinking about this, I think the propagator might be a constraint > linking M and A, as Gecode cannot unify the variables as ic does.... > > However, I was actually looking at argmin when I noticed that there > was a propagator attached when the constraint was satisfied, but I > decided to look at min instead as ic does not have argmin. > > I can't show the ECLiPSe execution with argmin, as that is on a VNC > window that I can't use cut and paste on, but here is what I tried: > > min_index([1,2,3,1,4], I), get_constraints_number(I, D). > > I = I{[1,4]} > D = 1 > > so there is 1 propagator attached to I in this case, when min_index > (argmin) is entailed. > > Cheers, > > Kish > > > _______________________________________________ > 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 _______________________________________________ Gecode users mailing list users@gecode.org https://www.gecode.org/mailman/listinfo/gecode-users
