[Scip] Segmentation Fault

[Julio Rojas]

I downloaded the binary for Linux32. Again thanks.
-------------------------------------------------
Julio Rojas
jcredberry at gmail.com


On Thu, Nov 19, 2009 at 11:29 AM, Stefan Vigerske
<stefan at math.hu-berlin.de>wrote:

> Hi,
>
> did you compile SCIP with CLP from source or you downloaded a binary?
>
> If you got it from source, go into the scip-1.2.0 directory and do
>  patch -p1 < scip.patch
> Then recompile.
> Or you can look at scip.patch and change things in the souce by hand.
> Important are those in lpi_clp.cpp and heur_trivial.c.
>
> If you downloaded a binary, then for which platform?
>
> Stefan
>
>
> Am 19.11.2009 11:21, schrieb Julio Rojas:
> > Thanks for the patch, but how can I apply it?
> > -------------------------------------------------
> > Julio Rojas
> > jcredberry at gmail.com
> >
> >
> > On Thu, Nov 19, 2009 at 11:16 AM, Stefan Vigerske
> > <stefan at math.hu-berlin.de>wrote:
> >
> >> Hi,
> >>
> >> there is a bug in the SCIP/CLP interface.
> >> The patch is attached.
> >>
> >> Stefan
> >>
> >> Am 19.11.2009 10:04, schrieb Julio Rojas:
> >>> Dear all, I have been using SCIP-CLP to solve some BIP problems of my
> PhD
> >>> work. One of the problems has the generic form:
> >>>
> >>> Min Sum(Xi)
> >>> s.t.
> >>> Xi+Xk <= 1, if Aik=1 and i<k, for i,k in {1,...,n}
> >>> Xi-Xk = 0, if {Xi,Xk} in Pj for all j in {1,...,g}, g<n
> >>> Sum(Xi)>=floor(n/2)+1
> >>> Xi in {0,1}
> >>>
> >>> I know that for some setups this problem is unfeasible, but sometimes I
> >> get
> >>> segmentation fault errors like in the attached example.
> >>>
> >>> I use the standalone solver. After loading it the message presented is
> >> the
> >>> following:
> >>>
> >>> original problem has 75 variables (0 bin, 75 int, 0 impl, 0 cont) and
> 846
> >>> constraints
> >>>
> >>> After presolve, the message is:
> >>>
> >>> presolving:
> >>> (round 1) 69 del vars, 690 del conss, 0 chg bounds, 0 chg sides, 0 chg
> >>> coeffs, 0 upgd conss, 1046 impls, 0 clqs
> >>> (round 2) 69 del vars, 842 del conss, 0 chg bounds, 0 chg sides, 0 chg
> >>> coeffs, 0 upgd conss, 1046 impls, 0 clqs
> >>> (round 3) 69 del vars, 842 del conss, 0 chg bounds, 0 chg sides, 0 chg
> >>> coeffs, 3 upgd conss, 1046 impls, 0 clqs
> >>> (round 4) 69 del vars, 842 del conss, 0 chg bounds, 0 chg sides, 0 chg
> >>> coeffs, 4 upgd conss, 1046 impls, 0 clqs
> >>> (round 5) 70 del vars, 842 del conss, 0 chg bounds, 2 chg sides, 4 chg
> >>> coeffs, 4 upgd conss, 1056 impls, 0 clqs
> >>> (round 6) 71 del vars, 843 del conss, 0 chg bounds, 3 chg sides, 6 chg
> >>> coeffs, 4 upgd conss, 1060 impls, 0 clqs
> >>> (round 7) 71 del vars, 846 del conss, 1 chg bounds, 5 chg sides, 8 chg
> >>> coeffs, 4 upgd conss, 1062 impls, 0 clqs
> >>> (round 8) 72 del vars, 846 del conss, 1 chg bounds, 5 chg sides, 8 chg
> >>> coeffs, 4 upgd conss, 1062 impls, 0 clqs
> >>> presolving (9 rounds):
> >>>  72 deleted vars, 846 deleted constraints, 1 tightened bounds, 0 added
> >>> holes, 5 changed sides, 8 changed coefficients
> >>>  1062 implications, 0 cliques
> >>> presolved problem has 3 variables (3 bin, 0 int, 0 impl, 0 cont) and 3
> >>> constraints
> >>>       1 constraints of type <knapsack>
> >>>       2 constraints of type <logicor>
> >>> Presolving Time: 0.01
> >>>
> >>> So, as you can see, the problem should be unfeasible, but when I run
> the
> >>> solving routine I get the following message:
> >>>
> >>>  time | node  | left  |LP iter| mem |mdpt |frac |vars |cons |ccons|cols
> >>> |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap
> >>> t 0.0s|     1 |     0 |     0 | 449k|   0 |   - |   3 |   3 |   3 |   0
> |
> >>> 0 |   0 |   0 |   0 |      --      | 1.192662e+03 |    Inf
> >>> t 0.0s|     1 |     0 |     0 | 449k|   0 |   - |   3 |   3 |   3 |   0
> |
> >>> 0 |   0 |   0 |   0 |      --      | 1.170286e+03 |    Inf
> >>> Segmentation fault
> >>>
> >>> Any idea on what's happening? Is there a way to avoid this problem? I'm
> >>> running the standalone solver from an R script, so I don't know if by
> >> using
> >>> C I can catch this problem. I don't program in C. Can I trust that when
> >> this
> >>> happens the solution is unfeasible? I can cope with this problem if it
> is
> >>> presented when the solution is unfeasible and some set of features
> exist
> >> in
> >>> the model.
> >>>
> >>> Thank you very much for your help.
> >>> -------------------------------------------------
> >>> Julio Rojas
> >>> jcredberry at gmail.com
> >>>
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Scip mailing list
> >>> Scip at zib.de
> >>> http://listserv.zib.de/mailman/listinfo/scip
> >>
> >>
> >
>
>
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