<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jul 30, 2014 at 12:34 PM, John Forrest <span dir="ltr"><<a href="mailto:john.forrest@fastercoin.com" target="_blank">john.forrest@fastercoin.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Matthew,<br>
<br>
<br>
Fixed in trunk - do you want it fixed in stable?<br></div></div></blockquote><div>Yes, please, if it's not too much trouble =). </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"><div>
<br>
OsiPresolve did dual tests before tightening bounds. As z has
positive cost and useless coefficient dual tests said put it to
lower bound i.e. 0.4. Tightening then said integer variable is
fixed to 0.4 so infeasible. I said it was a stupid bug.<br></div></div></blockquote><div>Stupid and subtle; I'm glad I could help! It might be reasonable to add it as a Cbc unit test if you feel so inclined.</div>
<div><br></div><div>Cheers,</div><div>Matt </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#FFFFFF" text="#000000"><div>
<br>
Just moved tightening before dual tests.<span class="HOEnZb"><font color="#888888"><br>
<br>
John</font></span><div><div class="h5"><br>
On 30/07/14 18:17, Matthew Gidden wrote:<br>
</div></div></div><div><div class="h5">
<blockquote type="cite">
<div dir="ltr">Hi John,
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Wed, Jul 30, 2014 at 12:11 PM,
John Forrest <span dir="ltr"><<a href="mailto:john.forrest@fastercoin.com" target="_blank">john.forrest@fastercoin.com</a>></span>
wrote:<br>
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<div>Matthew,<br>
<br>
Should be easy to fix - looks like a really stupid
bug.<br>
<br>
If I change the lower bounds on y,z to 2,1 it works!
As rounding up should be first thing that happens, you
can see why I say stupid.<br>
</div>
</div>
</blockquote>
<div>Ok, thanks John! I can change my bounds on my unit test
for now, but I'm glad I was able to bring this to your
attention. Thanks again for looking into it.</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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<div> <br>
John Forrest
<div>
<div><br>
<br>
On 30/07/14 16:20, Matthew Gidden wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div>
<div dir="ltr">Hi all,
<div><br>
</div>
<div>I've been posting a lot recently.. first of
all, thank you for replying!</div>
<div><br>
</div>
<div>I've unit tested my application pretty
vigorously, and a Cbc API unit test broke when
I moved to the CLI implementation.
Specifically, I set up the following toy
problem:</div>
<div><br>
</div>
<div>min 2x + 0.5y + 1.8z</div>
<div>st x + y > 4.4</div>
<div> y + z < 3.1</div>
<div>x in [1.3, 5], y in [1.7, 5], z in [0.4, 5]</div>
<div>y, z integer<br clear="all">
<div><br>
</div>
<div>The unit test originally passed using the
OsiCbcSolverInterface's initial solve and
branch and bound methods. I updated it to
use an OsiClpSolverInterface that is fed a
CbcModel and call CbcMain0/1 on said model.
The unit test now fails with the following
relevant output:</div>
<div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Welcome
to the CBC MILP Solver <br>
Version: 2.8.7 <br>
Build Date: Dec 28 2013 <br>
command line - exchng -solve -quit
(default strategy 1)<br>
Continuous objective value is 5.47 - 0.00
seconds<br>
Cgl0000I Cut generators found to be
infeasible! (or unbounded)<br>
Pre-processing says infeasible or
unbounded</blockquote>
</div>
<div><br>
</div>
<div>To double check that indeed a feasible
solution existed, I solved the maximization
form of the same instance. Attached are MPS
files for the max and min forms, and I have
verified the same behavior using the cbc CLI
(i.e., min is returned as infeasible and max
solves). </div>
<div><br>
</div>
<div>I'm curious if anyone can replicate this
and/or has any advice.</div>
<div><br>
</div>
<div>Cheers,</div>
<div><br>
</div>
-- <br>
<div dir="ltr">Matthew Gidden<br>
Ph.D. Candidate, Nuclear Engineering
<div> The University of Wisconsin -- Madison<br>
Ph. <a href="tel:225.892.3192" value="+12258923192" target="_blank">225.892.3192</a><br>
</div>
</div>
</div>
</div>
<br>
<fieldset></fieldset>
<br>
</div>
</div>
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</pre>
</blockquote>
<br>
</div>
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<br>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
<div dir="ltr">Matthew Gidden<br>
Ph.D. Candidate, Nuclear Engineering
<div>The University of Wisconsin -- Madison<br>
Ph. <a href="tel:225.892.3192" value="+12258923192" target="_blank">225.892.3192</a><br>
</div>
</div>
</div>
</div>
</blockquote>
<br>
</div></div></div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div dir="ltr">Matthew Gidden<br>Ph.D. Candidate, Nuclear Engineering<div>The University of Wisconsin -- Madison<br>Ph. 225.892.3192<br></div></div>
</div></div>