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<div class="moz-cite-prefix">Marco,<br>
<br>
The bad cut looks like -<br>
<br>
cut has violation of 0.666667 value 1.66667<br>
[9,0.333333] [11,-0.333333] [15,-3.33333] [4,0.666667] [8,-2]
[12,0.666667] [13,0.666667] [14,0.666667] [17,0.666667] <= -18<br>
<br>
Of course the numbers are not exactly that and four entries are
for continuous variables. If they had all been integral then I
think cut would have been cleaned up. As it is the cut made the
problem infeasible by 4e-7.<br>
<br>
If there had been more variables in cut and some non integer then
the cut would have been relaxed a tiny bit.<br>
<br>
As I don't want to make sudden changes, I have changed the code a
bit so that you can define the number of variables in cut (with
some non integer) when the cut will be relaxed a bit.<br>
<br>
To do this you have to configure with -DGOMORY_RELAX_NUMBER=n.
(n==5) works for you. This only affects cuts with non integer
variables.<br>
<br>
John<br>
<br>
On 10/08/15 07:50, mg wrote:<br>
</div>
<blockquote
cite="mid:CAOayR=Z_v-9qLekMtNaRigdmGqujTehN963ck3ZPt4O+dUtMag@mail.gmail.com"
type="cite">
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<div dir="ltr">Sorry, here's the missing attachment
<div><br>
</div>
<div>Regards,</div>
<div>Marco</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2015-07-28 15:36 GMT+02:00 John Forrest
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:john.forrest@fastercoin.com" target="_blank">john.forrest@fastercoin.com</a>></span>:<br>
<blockquote class="gmail_quote">
<div>
<div>Attached????????????
<div>
<div class="h5"><br>
<br>
On 24/07/15 08:29, mg wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div class="h5">
<div dir="ltr">Hi All,
<div>if I remember correctly in version 2.9.4,
gomory cuts generator started to give some
problems causing false infeasibilities. In
theory, version 2.9.5 contains some fixes for
this issue, but I think it's not completely
corrected since I've found a model that appears
infeasible unless you disable gomory cuts.</div>
<div><br>
</div>
<div>Attached you can find the LP file. Please
note that I'm running this model through
callCbc(), and you need to disable heuristics
otherwise DiveCoefficient will find a solution
before gomory cuts "too much"..</div>
<div><br>
</div>
<div>Here's a piece of code to reproduce the
problem :</div>
<div><br>
</div>
<div>
<div>OsiClpSolverInterface solver;</div>
<div>CbcModel model(solver);</div>
<div>model.solver()->readLp("infeas.lp");<br>
</div>
</div>
<div>
<div>std::string args("-heur off -solve"); //
using "-gomory off -solve" it works</div>
<div>callCbc(args, model);</div>
</div>
<div><br>
</div>
<div>Thanks in advance,</div>
<div>Marco</div>
</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
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