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<div class="moz-cite-prefix">David,<br>
<br>
Could be something to do with restarting search. It looks as if
Cbc did 100 nodes and saw it could fix variables (because of
getting a solution) to make problem smaller. So it solves that
smaller problem.<br>
<br>
a) might explain times - maybe it took 900 seconds to do those
first nodes???<br>
b) may be a bug with max time and restarting (may also explain
preprocessing problem)<br>
<br>
What happens if you add -strategy 0 - that should switch off
restart?<br>
<br>
If you want, send the mps file to me - I presume it is only a few
megabytes compressed.<br>
<br>
John Forrest<br>
<br>
On 05/03/14 18:51, David Einstein wrote:<br>
</div>
<blockquote
cite="mid:CAHr4SdYZKhsyLKdu8PPoyyAk+GKnaD1t1-TG=swDrTM4xrtVMw@mail.gmail.com"
type="cite">
<div dir="ltr">
<div><font color="#000000" face="arial, sans-serif">(attaching
large mps files is not allowed, so I'm resending)</font></div>
<div><font color="#000000" face="arial, sans-serif"><br>
</font></div>
<span
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">I
am calling libCbcSolver as follows ( cbc 2.8 windows 7 64 bit)</span>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">
<br>
</div>
<blockquote
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px;margin:0px
0px 0px 40px;border:none;padding:0px">
<div> CbcModel cbc(osi);</div>
<div> CbcMain0(cbc);</div>
<div> cbc.setDblParam(CbcModel::CbcMaximumSeconds, 1800);</div>
<div> const char *argv2[] = {"schedulemip", "-preprocess",
"off", "-solve", "-quit"};</div>
<div> CbcMain1(5, argv2, cbc); </div>
</blockquote>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">
<br>
</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">and
the tail end of the output looks like</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------</div>
<blockquote
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px;margin:0px
0px 0px 40px;border:none;padding:0px">
<div>Cbc0010I After 10800 nodes, 1166 on tree, 169460.67 best
solution, best possible 157572.58 (804.68 seconds)</div>
<div>Cbc0010I After 10900 nodes, 1214 on tree, 169460.67 best
solution, best possible 157572.58 (810.69 seconds)</div>
<div>Cbc0010I After 11000 nodes, 1264 on tree, 169460.67 best
solution, best possible 157572.58 (815.13 seconds)</div>
<div>Cbc0010I After 11100 nodes, 1311 on tree, 169460.67 best
solution, best possible 158109.85 (835.74 seconds)</div>
<div>Cbc0010I After 11200 nodes, 1361 on tree, 169460.67 best
solution, best possible 158345.27 (853.65 seconds)</div>
<div>Cbc0010I After 11300 nodes, 1411 on tree, 169460.67 best
solution, best possible 158404.02 (869.75 seconds)</div>
<div>Cbc0010I After 11400 nodes, 1461 on tree, 169460.67 best
solution, best possible 158464.46 (886.81 seconds)</div>
<div>Cbc0020I Exiting on maximum time</div>
<div>Cbc0005I Partial search - best objective 169460.67 (best
possible 158464.46), took 1871577 iterations and 11482 nodes
(900.43 seconds)</div>
<div>Cbc0032I Strong branching done 8334 times (76189
iterations), fathomed 9 nodes and fixed 1 variables</div>
<div>Cbc0035I Maximum depth 124, 223498 variables fixed on
reduced cost</div>
<div>Cbc0038I Probing was tried 1579 times and created 82296
cuts of which 1 were active after adding rounds of cuts
(11.281 seconds)</div>
<div>
Cbc0038I Gomory was tried 7626 times and created 8129 cuts
of which 2464 were active after adding rounds of cuts
(144.295 seconds)</div>
<div>Cbc0038I Knapsack was tried 2 times and created 0 cuts of
which 0 were active after adding rounds of cuts (0.016
seconds)</div>
<div>Cbc0038I Clique was tried 2 times and created 0 cuts of
which 0 were active after adding rounds of cuts (0.000
seconds)</div>
<div>Cbc0038I MixedIntegerRounding2 was tried 2 times and
created 0 cuts of which 0 were active after adding rounds of
cuts (0.031 seconds)</div>
<div>Cbc0038I FlowCover was tried 2 times and created 0 cuts
of which 0 were active after adding rounds of cuts (0.000
seconds)</div>
<div>Cbc0038I TwoMirCuts was tried 1579 times and created 10
cuts of which 1 were active after adding rounds of cuts
(3.860 seconds)</div>
<div>Cbc0038I Stored from first was tried 7626 times and
created 350 cuts of which 179 were active after adding
rounds of cuts (0.000 seconds)</div>
<div>Cbc0001I Search completed - best objective
184071.9400000001, took 1886804 iterations and 11532 nodes
(900.65 seconds)</div>
<div>Cbc0032I Strong branching done 428 times (5741
iterations), fathomed 0 nodes and fixed 0 variables</div>
<div>Cbc0035I Maximum depth 34, 0 variables fixed on reduced
cost</div>
<div>Cuts at root node changed objective from 156922 to 157294</div>
<div>Probing was tried 3 times and created 0 cuts of which 0
were active after adding rounds of cuts (0.032 seconds)</div>
<div>Gomory was tried 24 times and created 61 cuts of which 28
were active after adding rounds of cuts (1.650 seconds)</div>
<div>Knapsack was tried 3 times and created 0 cuts of which 0
were active after adding rounds of cuts (0.016 seconds)</div>
<div>Clique was tried 3 times and created 0 cuts of which 0
were active after adding rounds of cuts (0.000 seconds)</div>
<div>MixedIntegerRounding2 was tried 3 times and created 0
cuts of which 0 were active after adding rounds of cuts
(0.031 seconds)</div>
<div>FlowCover was tried 1 times and created 0 cuts of which 0
were active after adding rounds of cuts (0.000 seconds)</div>
<div>TwoMirCuts was tried 3 times and created 5 cuts of which
0 were active after adding rounds of cuts (0.624 seconds)</div>
<div><br>
</div>
<div>Result - Optimal solution found</div>
<div><br>
</div>
<div>Objective value: 184071.94000000</div>
<div>Enumerated nodes: 11532</div>
<div>Total iterations: 1886804</div>
<div>Time (CPU seconds): 901.01</div>
<div>Time (Wallclock seconds): 901.01</div>
<div><br>
</div>
<div>Total time (CPU seconds): 901.50 (Wallclock
seconds): 901.49</div>
</blockquote>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px"> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px"><br>
</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">Things
that baffle me:</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">
1) It is timing out after 900 seconds instead of 1800</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">2)
It is reporting 184071.94 as optimal when it has found a
solution of 169460.67</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">
<br>
</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">I
am running with preprocesssing off because I get the following
with it on</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">
<br>
</div>
<blockquote
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px;margin:0px
0px 0px 40px;border:none;padding:0px">
<div>Coin0505I Presolved problem not optimal, resolve after
postsolve</div>
<div>Coin0505I Presolved problem not optimal, resolve after
postsolve</div>
<div>Cgl0013I Postprocessed model is infeasible - possible
tolerance issue - try without preprocessing</div>
<div>1 relaxed row infeasibilities - summing to 1</div>
<div>1 relaxed row infeasibilities - summing to 1</div>
<div>
1 relaxed row infeasibilities - summing to 1</div>
<div><br>
</div>
<div>Result - Stopped on time limit</div>
<div><br>
</div>
<div>Objective value: 173347.10500000</div>
<div>Lower bound: 159327.768</div>
<div>Gap: 0.09</div>
<div>Enumerated nodes: 23597</div>
<div>Total iterations: 4755507</div>
<div>Time (CPU seconds): 1800.63</div>
</blockquote>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">
<br>
</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px"><br>
</div>
<div
style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:13px">Am
I doing something wrong?</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
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</pre>
</blockquote>
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