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<p>Which version of cbc are you running? It is solving to the
optimal and then core dumping?<br>
</p>
<p>cbc -import problem.lp -min -solve<br>
Welcome to the CBC MILP Solver <br>
Version: 2.8.12 <br>
Build Date: Feb 22 2016 <br>
<br>
command line - cbc -import problem.lp -min -solve (default
strategy 1)<br>
Continuous objective value is 0 - 0.00 seconds<br>
Cgl0003I 0 fixed, 9 tightened bounds, 1 strengthened rows, 0
substitutions<br>
Cgl0004I processed model has 7 rows, 164 columns (164 integer) and
636 elements<br>
Cutoff increment increased from 1e-05 to 0.9999<br>
Cbc0038I Pass 1: suminf. 0.30901 (2) obj. 70.3063 iterations
3<br>
Cbc0038I Solution found of 70.3063<br>
Cbc0038I Branch and bound needed to clear up 2 general integers<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 4 rows 25
columns<br>
Cbc0038I Cleaned solution of 31480<br>
Cbc0038I Before mini branch and bound, 160 integers at bound fixed
and 0 continuous<br>
Cbc0038I Mini branch and bound improved solution from 31480 to
31480 (0.04 seconds)<br>
Cbc0038I Round again with cutoff of 28331.1<br>
Cbc0038I Pass 2: suminf. 0.30901 (2) obj. 70.3063 iterations
0<br>
Cbc0038I Solution found of 70.3063<br>
Cbc0038I Branch and bound needed to clear up 2 general integers<br>
Cbc0038I Full problem 8 rows 164 columns, reduced to 4 rows 14
columns<br>
Cbc0038I Mini branch and bound could not fix general integers<br>
Cbc0038I No solution found this major pass<br>
Cbc0038I Before mini branch and bound, 160 integers at bound fixed
and 0 continuous<br>
Cbc0038I Mini branch and bound did not improve solution (0.04
seconds)<br>
Cbc0038I After 0.04 seconds - Feasibility pump exiting with
objective of 31480 - took 0.02 seconds<br>
Cbc0012I Integer solution of 31480 found by feasibility pump after
0 iterations and 0 nodes (0.04 seconds)<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 3 rows 5
columns<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 2 rows 3
columns<br>
Cbc0031I 3 added rows had average density of 91.666667<br>
Cbc0013I At root node, 3 cuts changed objective from 0 to 0 in 38
passes<br>
Cbc0014I Cut generator 0 (Probing) - 1 row cuts average 2.0
elements, 2 column cuts (2 active) in 0.052 seconds - new
frequency is -100<br>
Cbc0014I Cut generator 1 (Gomory) - 49 row cuts average 162.6
elements, 0 column cuts (0 active) in 0.016 seconds - new
frequency is -100<br>
Cbc0014I Cut generator 2 (Knapsack) - 0 row cuts average 0.0
elements, 0 column cuts (0 active) in 0.000 seconds - new
frequency is -100<br>
Cbc0014I Cut generator 3 (Clique) - 0 row cuts average 0.0
elements, 0 column cuts (0 active) in 0.000 seconds - new
frequency is -100<br>
Cbc0014I Cut generator 4 (MixedIntegerRounding2) - 43 row cuts
average 140.8 elements, 0 column cuts (0 active) in 0.004 seconds
- new frequency is -100<br>
Cbc0014I Cut generator 6 (TwoMirCuts) - 14 row cuts average 150.1
elements, 0 column cuts (0 active) in 0.000 seconds - new
frequency is -100<br>
Cbc0010I After 0 nodes, 1 on tree, 31480 best solution, best
possible 0 (0.14 seconds)<br>
Cbc0016I Integer solution of 11580 found by strong branching after
238 iterations and 20 nodes (0.15 seconds)<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 7 rows 8
columns<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 6 rows 7
columns<br>
Cbc0016I Integer solution of 8600 found by strong branching after
474 iterations and 87 nodes (0.18 seconds)<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 7 rows 9
columns<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 4 rows 7
columns<br>
Cbc0012I Integer solution of 1025 found by RINS after 482
iterations and 91 nodes (0.19 seconds)<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 7 rows 12
columns<br>
Cbc0012I Integer solution of 825 found by combine solutions after
482 iterations and 91 nodes (0.19 seconds)<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 3 rows 7
columns<br>
Cbc0004I Integer solution of 70 found after 1719 iterations and
372 nodes (0.27 seconds)<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 7 rows 13
columns<br>
Cbc0038I Full problem 7 rows 164 columns, reduced to 4 rows 8
columns<br>
cbc: CbcModel.cpp:15284: int CbcModel::doOneNode(CbcModel*,
CbcNode*&, CbcNode*&): Assertion `feasible' failed.<br>
Aborted (core dumped)<br>
</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">On 28/12/2017 5:58 AM, Rhavar wrote:<br>
</div>
<blockquote type="cite"
cite="mid:aDfWRq1jMTtXsITBlKZ4qD8AwRdAKRX-GhPkyl3joIoMs55rxUzWR5r1O0SzsFNshV1V7zHRFwudi9KtmXXsEDivaO8zd9wSXZo9r-yndnM=@protonmail.com">
<div>I just realized, an easy way to prove the solver is finding a
suboptimal solution is by forcing it's hand and adding an
additional constraint:<br>
</div>
<div><br>
</div>
<div>force: i22 = 1<br>
</div>
<div><br>
</div>
<div>and you will see it returns a better solution that it didn't
see before</div>
<div><br>
</div>
<div class="protonmail_signature_block">
<div class="protonmail_signature_block-user">
<div>-Ryan<br>
</div>
</div>
<div class="protonmail_signature_block-proton
protonmail_signature_block-empty"><br>
</div>
</div>
<div><br>
</div>
<blockquote type="cite" class="protonmail_quote">
<div>-------- Original Message --------<br>
</div>
<div>Subject: Suboptimal solution as optimal?<br>
</div>
<div>Local Time: December 27, 2017 12:37 PM<br>
</div>
<div>UTC Time: December 27, 2017 6:37 PM<br>
</div>
<div>From: <a class="moz-txt-link-abbreviated" href="mailto:rhavar@protonmail.com">rhavar@protonmail.com</a><br>
</div>
<div>To: <a class="moz-txt-link-abbreviated" href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a> <a class="moz-txt-link-rfc2396E" href="mailto:cbc@list.coin-or.org"><cbc@list.coin-or.org></a><br>
</div>
<div><br>
</div>
<div>I have a problem:<br>
</div>
<div><a
href="https://gist.github.com/RHavar/dfb9de631363ecb9e1c326fff5ebd09b"
moz-do-not-send="true">https://gist.github.com/RHavar/dfb9de631363ecb9e1c326fff5ebd09b</a><br>
</div>
<div><br>
</div>
<div>(lp file and solution file attached)<br>
</div>
<div><br>
</div>
<div>In the solution it says: "Optimal - objective value" but I
think I have found a superior solution by hand:<br>
</div>
<div><br>
</div>
<div><span class="s1"><span class="Apple-converted-space"> </span>o6
= 1</span><br>
</div>
<div>i22 = 1<br>
</div>
<div><br>
</div>
<div>Which gives a better objective (<span class="s1">70 instead
of </span>825)<br>
</div>
<div><br>
</div>
<div>--<br>
</div>
<div><br>
</div>
<div>So I guess my question is, does "Optimal - objective
value" mean that it's guaranteed to be the optimal solution?
Or am I doing something wrong? Or is there a bug in cbc? <br>
</div>
<div><br>
</div>
<div><br>
</div>
<div class="protonmail_signature_block">
<div class="protonmail_signature_block-user">
<div>-Ryan<br>
</div>
</div>
<div class="protonmail_signature_block-proton
protonmail_signature_block-empty"><br>
</div>
</div>
<div><br>
</div>
</blockquote>
<div><br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
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</pre>
</blockquote>
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