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Hi Domnik,</div>
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<br>
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I've worked out what's going on here and it's not a problem with SCIP. I had some constraint handlers of my own for which I had not implemented the copy methods. So when a heuristic made a copy for a subSCIP some constraints were missing and so we got primal
solutions suggested which should not have been.</div>
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<br>
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After implementing the missing copy methods this problem went away.</div>
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Thanks for your input,</div>
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<br>
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James<br>
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James Cussens</div>
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Room MVB 3.26</div>
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School of Computer Science, University of Bristol</div>
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Phone: +44 (0)117 455 8723</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Kamp, Dominik <Dominik.Kamp@uni-bayreuth.de><br>
<b>Sent:</b> 01 August 2023 17:26<br>
<b>To:</b> James Cussens <james.cussens@bristol.ac.uk><br>
<b>Cc:</b> scip@zib.de <scip@zib.de><br>
<b>Subject:</b> Re: [SCIP] question on a warning</font>
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<div class="PlainText">Hello James,<br>
<br>
you are right. Since the objective value from the warning does not correspond to the main objective value, the warning must be thrown by a subscip. These warnings can be triggered due to numerics but there is also the chance that you have found a bug. Therefore,
we would be very glad if you could share the corresponding instance with us (or file a bug report), so that we can get to the bottom of this potential issue.<br>
<br>
Best regards,<br>
<br>
Dominik<br>
<br>
> Am 01.08.2023 um 18:03 schrieb James Cussens <james.cussens@bristol.ac.uk>:<br>
> <br>
> Hi all,<br>
> <br>
> I am getting the following warning:<br>
> <br>
> time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.<br>
> 0.0s| 1 | 0 | 39 | - | 1118k | 0 | 20 | 36 | 63 | 30 | 31 | 1 | 0 |-1.804449e+02 | 0.000000e+00*| Inf | unknown<br>
> 0.0s| 1 | 0 | 40 | - | 1118k | 0 | 20 | 36 | 64 | 31 | 32 | 1 | 0 |-1.802198e+02 | 0.000000e+00*| Inf | unknown<br>
> 0.0s| 1 | 0 | 41 | - | 1124k | 0 | 20 | 36 | 65 | 32 | 33 | 1 | 0 |-1.801160e+02 | 0.000000e+00*| Inf | unknown<br>
> 0.1s| 1 | 2 | 41 | - | 1128k | 0 | 20 | 36 | 65 | 32 | 34 | 1 | 15 |-1.800907e+02 | 0.000000e+00*| Inf | unknown<br>
> r 0.1s| 15 | 14 | 57 | 1.1 |rounding| 14 | 20 | 36 | 65 | 33 | 0 | 1 | 42 |-1.758398e+02 |-1.151438e+01 |1427.13%| unknown<br>
> r 0.1s| 16 | 15 | 65 | 1.6 |rounding| 15 | 20 | 36 | 65 | 33 | 0 | 1 | 45 |-1.758398e+02 |-1.604484e+01 | 995.93%| unknown<br>
> * 0.1s| 17 | 14 | 66 | 1.6 | LP | 16 | 20 | 36 | 65 | 33 | 1 | 1 | 45 |-1.758398e+02 |-2.039660e+01 | 762.10%| unknown<br>
> r 0.1s| 24 | 17 | 78 | 1.6 |rounding| 16 | 20 | 36 | 66 | 35 | 0 | 1 | 50 |-1.758398e+02 |-2.640592e+01 | 565.91%| unknown<br>
> * 0.1s| 34 | 21 | 95 | 1.6 | LP | 17 | 20 | 36 | 69 | 39 | 1 | 1 | 54 |-1.758398e+02 |-2.719577e+01 | 546.57%| unknown<br>
> * 0.1s| 37 | 22 | 99 | 1.6 | LP | 18 | 20 | 36 | 70 | 40 | 1 | 1 | 54 |-1.758398e+02 |-6.270300e+01 | 180.43%| unknown<br>
> r 0.2s| 57 | 30 | 144 | 1.8 |rounding| 18 | 20 | 36 | 72 | 54 | 1 | 1 | 61 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> 0.2s| 100 | 63 | 235 | 2.0 | 1345k | 18 | 20 | 36 | 69 | 73 | 2 | 1 | 69 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> 0.3s| 200 | 159 | 480 | 2.2 | 1845k | 18 | 20 | 36 | 71 | 149 | 2 | 1 | 71 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> WARNING: Dual bound 69.0721 is larger than the objective of the primal solution 68.1511. The solution might not be optimal.<br>
> 0.5s| 300 | 253 | 758 | 2.4 | 2248k | 18 | 20 | 36 | 76 | 226 | 1 | 1 | 71 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> 0.6s| 400 | 351 | 1029 | 2.5 | 2670k | 18 | 20 | 36 | 73 | 312 | 1 | 1 | 71 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.<br>
> 0.7s| 500 | 443 | 1254 | 2.4 | 2799k | 18 | 20 | 36 | 70 | 367 | 1 | 1 | 71 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> 0.8s| 600 | 537 | 1467 | 2.4 | 3062k | 18 | 20 | 36 | 70 | 411 | 1 | 3 | 71 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> 1.0s| 700 | 633 | 1696 | 2.4 | 3247k | 18 | 20 | 36 | 70 | 470 | 1 | 3 | 71 |-1.758398e+02 |-6.485425e+01 | 171.13%| unknown<br>
> <br>
> SCIP Status : solving was interrupted [time limit reached]<br>
> <br>
> The solutions I am getting are fine and I have no obvious errors, but I am curious as to what might have generated the warning. Perhaps it comes from some subscip run by a heuristic since the dual bound the warning mentions (69.0721) is some distance from
that of the main problem ( -1.758398e+02). Can anyone explain what might be happening here; perhaps this indicates some problem I have not yet noticed.<br>
> <br>
> James<br>
> <br>
> James Cussens<br>
> Room MVB 3.26<br>
> Dept of Computer Science, University of Bristol<br>
> Phone: +44 (0)117 455 8723<br>
> <a href="https://jcussens.github.io/">https://jcussens.github.io/</a><br>
> Funded PhDs available in Bristol in the following areas: Data Science, Interactive AI, Cyber Security or Digital Health.
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