Yes, Kish. What I need is also done by precede/2 with lib(gfd). However, what I have noticed is that although in many cases lib(gfd) is faster than lib(ic)/lib(ic_global), which someone would expect to be the case, as a compiled C++ code should run faster than a Prolog program, there are cases where a lif(gfd) based CP program is quite slower than the equivalent one based on the native ECLiPSe constraint libraries. Best Rehards, Panagiotis On 27-Mar-23 4:57 PM, Kish Shen wrote: >> And, Hakan, thank you very much for the info on the value_precede_chain > > This constraint is implemented in Gecode, and is available for ECLiPSe > through lib(gfd) as precede/2: > > http://eclipseclp.org/doc/bips/lib/gfd/precede-2.html > > Most of Gecode's constraints are available to ECLiiPSe through > lib(gdfd). You can check on which constraints are in the various > ECLiPSe finite domain libraries at: > > http://eclipseclp.org/doc/bips/finite-domain_constraints.html > > Cheers, > > Kish > > > On Mon, Mar 27, 2023 at 11:28 AM Panagiotis Stamatopoulos > <takis_at_...90...> wrote: >> >> Yes, it worked!!! Marco, thank you very much, indeed! >> >> And, Hakan, thank you very much for the info on the value_precede_chain >> global constraint. It is exactly what I was looking for, but in an >> ECLiPSe environment. Marco's suggestion is actually a simple and >> correct implementation of it. >> >> Best Regards, >> Panagiotis >> >> On 27-Mar-23 12:58 PM, Panagiotis Stamatopoulos wrote: >>> Hi Marco, >>> >>> Yes, you are right. The ultimate purpose of this constraint is >>> symmetry breaking. I 'll try what you suggest. Thanks! >>> >>> Regards, >>> Panagiotis >>> >>> On 27-Mar-23 12:51 PM, Marco Gavanelli wrote: >>>> Hi Panagiotis, >>>> >>>> this constraint reminds me of a symmetry breaking labeling proposed by >>>> Pedro Meseguer. >>>> >>>> Anyway, what about: >>>> >>>> L[0] = 1 >>>> >>>> forall i>0 >>>> L[i] <= maxlist(L[0..(i-1)]) + 1 >>>> ? >>>> >>>> I hope the intuition is clear, with L[0..(1-i)] I mean the sublist of >>>> the first i elements of the list L. >>>> >>>> Best, >>>> Marco >>>> >>>> >>>> On 27/03/2023 11:34, Panagiotis Stamatopoulos wrote: >>>>> Hello Everybody, >>>>> >>>>> I am seeking ideas on how to implement in ECLiPSe a specific >>>>> constraint in a simple, if possible, and efficient way. >>>>> >>>>> Let L be a list of length N with domain variables ranging >>>>> in 1..M. Acceptable lists are the ones that ... >>>>> 1. ... contain values from 1 up to K (K =< M), but not any >>>>> values from K+1 up to M (K is not given). >>>>> 2. ... satisfy the condition that the first occurrences of >>>>> the values from 1 to K appear in this order in the list. >>>>> >>>>> For example, let N = 8 and M = 5. The lists [1,1,2,1,2,3,2,1] >>>>> and [1,2,1,3,2,4,3,1] are valid. The first one has K = 3 (only >>>>> items 1, 2, 3 appear in the list) and the second one has K = 4 >>>>> (just 5 is missing from the list). In the first list, the first >>>>> occurrences of 1, 2, 3 are in positions 1, 3, 6 and in the second >>>>> list, the first occurrences of 1, 2, 3, 4 are in positions 1, 2, >>>>> 4, 6 in the lists. All fine! >>>>> >>>>> I believe that the requirement 1 above could be implemented >>>>> easily with the occurrences constraint (one for each number in >>>>> 1..M) and a set of implication (=>) constraints, stating that >>>>> if the number of occurrences of x in 1..M is 0, then the numbers >>>>> of occurrences of x+1, x+2, ... in the list should also be 0. >>>>> I cannot predict the propagation level of this approach, but >>>>> it seems that, at least, declaratively can be stated. >>>>> >>>>> I don't have any good ideas for the requirement 2. I tried >>>>> something that exploits again the occurrences constraint (for >>>>> every number in 1..M and every prefix list of the given list) >>>>> and then the lex_le constraint. It worked, but if N is around >>>>> 50 or more, the efficiency is unacceptable. >>>>> >>>>> Any ideas on the above would be more than welcome. >>>>> >>>>> Best Regards, >>>>> Panagiotis >>>>> >>>>> >>>>> _______________________________________________ >>>>> ECLiPSe-CLP-Users mailing list >>>>> ECLiPSe-CLP-Users_at_lists.sourceforge.net >>>>> https://lists.sourceforge.net/lists/listinfo/eclipse-clp-users >>>> >>> >>> >>> _______________________________________________ >>> ECLiPSe-CLP-Users mailing list >>> ECLiPSe-CLP-Users_at_lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/eclipse-clp-users >> >> >> _______________________________________________ >> ECLiPSe-CLP-Users mailing list >> ECLiPSe-CLP-Users_at_lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/eclipse-clp-users > > > _______________________________________________ > ECLiPSe-CLP-Users mailing list > ECLiPSe-CLP-Users_at_lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/eclipse-clp-usersReceived on Mon Mar 27 2023 - 16:25:22 CEST
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