From: Oliver Shycle <oliver.shycle_at_googlemail.com>

Date: Wed, 31 Mar 2010 15:18:40 +0200

Date: Wed, 31 Mar 2010 15:18:40 +0200

Your example, Marco, is very clear and simple. Unfortunately it cannot be transformed to a solution for my general problem. Using reified constraints as proposed by Thorsten look interesting. I hope I can use them to construct my complex constraints somehow. Generally, I am sure there is a possible solution for every problem, as given by your examples. However, I wonder if ther isn't a more "intuitive" way of expressing constraints. As described in my first mail of this thread, why cant I have a constraint like "greater_eight/1", formulated as a prolog clause, and use it along with other "standard cosntraints" like #>, #\ etc.? As described in the first email, if ECLiPSe comes along such a constraint it evaluates to true without even having instantiated the variable to any value. Maybe I haven't understood something about constraints right!? Another example for behavior I dont understand is the following: X #< 8 => greater_eight(Y) This raises the error "calling an undefined procedure greater_eight" even if it is defined. I gues that is because greater_eight/1 is not recognized as a constraint. The operator "=>" however expects a constraint? Thanks for you help and forgive me that is is hard to express what my problem is :-) On 31 March 2010 14:47, Thorsten Winterer <thorsten_winterer_at_web.de> wrote: > Hello, > > you can use reified constraints to express "if any variable has a value > greater than eight, there must be at least one variable with a value smaller > than eight.": > > :- lib(ic). > :- lib(ic_global). > > test(L) :- > L = [X,Y,Z], > L #:: 1..10, > ( foreach(V,L),foreach(BG,BGs), foreach(BS,BSs) do > #>(V,8,BG), > #<(V,8,BS) > ), > sumlist(BGs,EG), > sumlist(BSs,ES), > (EG #>= 1) => (ES #>= 1), > X #= 9, > Y #= 9, > get_max(Z,Z). > > > For each variable V, BG is set to 1 if V > 8, else 0. BS is set to 1 if V < > 8, else 0. > If the sum of the BG values is at least 1, then the sum of the BS values > must also be at least 1. > > Now, if X and Y are instantiated to 9, the maximum value in Z's domain is > 7. > > Cheers, > Thorsten > > > Am 31.03.2010 14:27, schrieb Oliver Shycle: > > Hello, > > well I think the negation axample was not really good to express what i > want. Let me formulate the problem like this: > We stick to the variables and their domains as before. I need constraints > that express the following: "if any variable has a value greater than eight, > there must be at least one variable with a value smaller than eight." > ------------------------------- > example :- > OutputModel = [A, B, C, D], > A #:: 1..100, > B #:: 1..100, > C #:: 1..100, > D #:: 1..100, > > % constraints > > labeling(OutputModel), > writeln(OutputModel). > --------------------------------- > > I dont know how to express such kind of constraints. > Thanks for your help. > > Oliver. > > On 31 March 2010 11:02, Alexandre Saidi <Alexandre.Saidi_at_ec-lyon.fr>wrote: > >> Hi Olivier, >> I’m not sur i understand what you want to do with the negation. >> >> Tell me what if : >> example :- >> >> OutputModel = [A, B, C, D], >> A #:: 1..100, >> B #:: 1..100, >> C #:: 1..100, >> D #:: 1..100, >> >> #\+ (A #> 8 #\/ B#> 8 #\/ C #> 8 #\/ D#> 8), >> >> labeling(OutputModel), >> writeln(OutputModel). >> >> In both cases, constraint propagation will restrict variable domaine. >> It’s better not to use Disjunction (like member). >> >> Alex >> >> Le 30 mars 2010 à 09:57, Oliver Shycle a écrit : >> >> Hi all, >> >> I have a problem to express negated constraints in ECLiPSe. In my >> programm, I want to express what value certain interval constraints may NOT >> have. Consider the following problem description: the program shall find >> values for four variables such that the values are NOT greater than 8. >> >> Here's the code: >> ------------------------------------------------------ >> :- lib(ic). >> >> example :- >> >> OutputModel = [A, B, C, D], >> A #:: 1..100, >> B #:: 1..100, >> C #:: 1..100, >> D #:: 1..100, >> >> not(wrong_value(OutputModel)), >> labeling(OutputModel), >> writeln(OutputModel). >> >> wrong_value(Vars) :- >> member(Var, Vars), >> greater_eight(Var). >> >> greater_eight(X) :- >> X #> 8. >> ------------------------------------------------------ >> >> I know that I rather could limit the variable's domains to a maximum of 8, >> but I want to demonstrate my problem with this snippet. When ECLiPSe comes >> along the constraint "X #> 8" with the first variable of the list, the term >> evaluates to true. Therefore wrong_value evaluates to true without even >> setting up constraints for the other variables. The negation >> not(wrong_value(OutputModel)) thus becomes false and ECLiPSe sais it can't >> find a solution. If I test the code with a set of integers instead of >> variables everything works as expected. >> How can I tell ECLiPSe not to evaluate X #> 8 instantly, but keeping the >> constraint in mind for later instantiation during labeling/1? >> >> Many thanks for your help. >> >> Oliver. >> >> >> ------------------------------------------------------------------------------ >> Download Intel® Parallel Studio Eval >> Try the new software tools for yourself. Speed compiling, find bugs >> proactively, and fine-tune applications for parallel performance. >> See why Intel Parallel Studio got high marks during beta. >> >> http://p.sf.net/sfu/intel-sw-dev_______________________________________________ >> ECLiPSe-CLP-Users mailing list >> ECLiPSe-CLP-Users_at_lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/eclipse-clp-users >> >> >> ------------------------------- >> Alexandre Saidi >> Maitre de Conférences >> Ecole Centrale de Lyon-Dép. MI >> LIRIS-CNRS UMR 5205 >> Tél : 0472186530, Fax : 0472186443 >> >> >> >> >> >> >> > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta.http://p.sf.net/sfu/intel-sw-dev > > > _______________________________________________ > ECLiPSe-CLP-Users mailing listECLiPSe-CLP-Users@lists.sourceforge.nethttps://lists.sourceforge.net/lists/listinfo/eclipse-clp-users > > > > -- > Dr. Thorsten Winterer > A: Salzäckerstraße 178 > 70567 Stuttgart, Germany > T: +49 (0)711 6935080 > M: +49 (0)162 3240054 > E: thorsten_winterer_at_web.de > > > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > ECLiPSe-CLP-Users mailing list > ECLiPSe-CLP-Users_at_lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/eclipse-clp-users > >Received on Wed Mar 31 2010 - 13:18:47 CEST

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