Hi, in this case, you can impose the constraint lex_le on every two consecutive columns of the matrix. Cheers, Marco On 26/01/12 17:29, Bogdan Tanasa wrote: > Hi, > > A solution is an instantiation of that matrix. > Any permutation of the columns of that matrix represents the same solution. > > How can I avoid this situation in CLP? > > Thanks, > Bogdan. > > -----Original Message----- > From: Marco Gavanelli [mailto:marco.gavanelli_at_unife.it] > Sent: 26 ianuarie 2012 16:13 > To: eclipse-clp-users_at_lists.sourceforge.net > Subject: Re: [eclipse-clp-users] Symmetry > > On 26/01/12 15:09, Bogdan Tanasa wrote: >> I have a problem for which the boolean optimization variables are of the >> following form (a matrix): >> >> >> >> x_11, x_12, .., x_1n >> >> x_21, x_22, .., x_2n >> >> . >> >> x_n1, x_n2, .., x_nn >> >> >> >> In my case a solution of the form >> >> 0 1 0 1 >> >> 0 0 0 1 >> >> 0 1 0 1 >> >> Is identical with >> >> 1 0 1 0 >> >> 0 0 1 0 >> >> 1 0 1 0 >> >>> From the cost function point of view. >> >> >> >> Can you please tell me how to ignore exploring the symmetrical solutions > of >> this form ? > > To avoid this symmetry (this very symmetry), you can add the constraint: > > X_11 #\= 0 or X_12 #\= 1 or X_13 #\= 0 or X_14 #\= 1 or > X_21 #\= 0 or X_22 #\= 0 or X_23 #\= 0 or X_24 #\= 1 or > X_31 #\= 0 or X_32 #\= 1 or X_33 #\= 0 or X_34 #\= 1 > > If you want something more general, you might want to explain in more > detail why these two solutions are symmetric in your problem. > > Best, > Marco > -- Marco Gavanelli, Ph.D. in Computer Science Dept of Engineering University of Ferrara Tel/Fax +39-0532-97-4833 http://www.ing.unife.it/docenti/MarcoGavanelli/Received on Thu Jan 26 2012 - 16:58:16 CET
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