From: Marco Gavanelli <marco.gavanelli_at_unife.it>

Date: Sun, 05 Oct 2008 11:57:21 +0200

Date: Sun, 05 Oct 2008 11:57:21 +0200

Ulrich Scholz wrote: > Dear all, > > I have a question about the Integer Sets library: How is the performance > related to the initial size of the domains? > > Assume you have a Integer Sets constraint problem and the initial domains of > the variables are subsets of the set {1, ..., N1}. > > Furthermore, assume that the problem's solution is invariant regarding > increasing initial domain size. So, for example, it would have the same > solution (*) if we chose the initial domain size to be subsets of the set > {1, ..., N2}, N2 > N1. > > Now we increase N2. How does the performance behave? > > > The reason I ask is: Set variables have to be defined with a domain. In my > application, the number of variables and their relation (subset, \=, etc.) > are known before the actual domains of the variables. So I have to "guess" > their domains. If there is no performace penalty, I just choose the domains > "large enough". Dear Ulrich, I am not an expert, and I was waiting for other people to answer, but since you got no reply, even a non-expert comment might be useful. I think that the performance of constraint propagation should not change that much if you take a large domain. However, if you have a search procedure that checks all the combinations, of course the search space grows exponentially with the number of elements in the upper bound. Hope that helps. Cheers, Marco -- Marco Gavanelli, Ph.D. in Computer Science Dept of Engineering University of Ferrara Via Saragat 1 - 44100 Ferrara (Italy) Tel +39-0532-97-4833 Fax +39-0532-97-4870 http://www.ing.unife.it/docenti/MarcoGavanelli/Received on Sun Oct 05 2008 - 10:21:46 CEST

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