<div dir="ltr">CLP:<div><span style="font-size:12.8px">Problem 30n20b8 has 576 rows, 18380 columns and 109706 elements</span><br></div><div><span style="font-size:12.8px">CBS:</span></div><div><span style="font-size:12.8px">Cbc0038I Full problem 491 rows 8028 columns, reduced to 366 rows 423 columns</span><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px"><br></span></div><div><span style="font-size:12.8px">Are you sure you're comparing the same problem?</span></div><div><span style="font-size:12.8px"><br></span></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jun 26, 2017 at 11:30 AM, <span dir="ltr"><<a href="mailto:ycollette.nospam@free.fr" target="_blank">ycollette.nospam@free.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">At the beginning of the cbc run, I got this in the logs:<br>
<br>
Cbc0038I Full problem 491 rows 8028 columns, reduced to 366 rows 423 columns<br>
Cbc0038I Mini branch and bound did not improve solution (1.51 seconds)<br>
Cbc0038I After 1.51 seconds - Feasibility pump exiting - took 0.98 seconds<br>
Cbc0031I 59 added rows had average density of 233.55932<br>
Cbc0013I At root node, 59 cuts changed objective from 43.335573 to 86.107549 in 20 passes<br>
Cbc0014I Cut generator 0 (Probing) - 283 row cuts average 172.1 elements, 0 column cuts (0 active) in 1.322 seconds - new frequency is 1<br>
Cbc0014I Cut generator 1 (Gomory) - 15 row cuts average 743.3 elements, 0 column cuts (0 active) in 0.283 seconds - new frequency is -100<br>
Cbc0014I Cut generator 2 (Knapsack) - 0 row cuts average 0.0 elements, 0 column cuts (0 active) in 0.045 seconds - new frequency is -100<br>
Cbc0014I Cut generator 3 (Clique) - 0 row cuts average 0.0 elements, 0 column cuts (0 active) in 0.005 seconds - new frequency is -100<br>
Cbc0014I Cut generator 4 (MixedIntegerRounding2) - 50 row cuts average 224.3 elements, 0 column cuts (0 active) in 0.075 seconds - new frequency is 1<br>
Cbc0014I Cut generator 5 (FlowCover) - 0 row cuts average 0.0 elements, 0 column cuts (0 active) in 0.092 seconds - new frequency is -100<br>
Cbc0014I Cut generator 6 (TwoMirCuts) - 78 row cuts average 236.0 elements, 0 column cuts (0 active) in 0.169 seconds - new frequency is 1<br>
<br>
<br>
----- Mail original -----<br>
De: "ycollette nospam" <<a href="mailto:ycollette.nospam@free.fr">ycollette.nospam@free.fr</a>><br>
À: "cbc" <<a href="mailto:cbc@list.coin-or.org">cbc@list.coin-or.org</a>><br>
Envoyé: Lundi 26 Juin 2017 16:28:31<br>
Objet: [Cbc] Convergence problem with miplib2010/30n20b8<br>
<div><div class="h5"><br>
Hello,<br>
<br>
I am trying to run somes tests from miplib2010. And I meet some strange behavior.<br>
If I run clp on 30n20b8.mps without specific options, it converges quickly to a solution:<br>
<br>
At line 1 NAME 30n20b8<br>
At line 2 ROWS<br>
At line 580 COLUMNS<br>
At line 110291 RHS<br>
At line 110322 BOUNDS<br>
At line 128761 ENDATA<br>
Problem 30n20b8 has 576 rows, 18380 columns and 109706 elements<br>
Model was imported from /home/artelys/repository/coin/<wbr>Cbc/build/Dependencies/.//<wbr>MIPLIB2000/src/EP_MIPLIB2000/<wbr>instances/miplib2010/30n20b8.<wbr>mps.gz in 0.114319 seconds<br>
Presolve 493 (-83) rows, 11093 (-7287) columns and 63118 (-46588) elements<br>
Perturbing problem by 0.001%%of 301.52267 - largest nonzero change 0.00028965583 ( 9.6064362e-05%%) - largest zero change 0.00028962251<br>
0 Obj 0.041886881 Primal inf 253.60538 (88)<br>
78 Obj 0.044696222 Primal inf 359.4158 (159)<br>
142 Obj 0.04542365 Primal inf 105.42604 (119)<br>
214 Obj 0.045885186 Primal inf 83.292978 (114)<br>
298 Obj 0.046155092 Primal inf 32.89186 (74)<br>
380 Obj 0.048508765 Primal inf 87.130897 (64)<br>
464 Obj 0.057466585 Primal inf 99.796642 (62)<br>
548 Obj 0.068410705 Primal inf 276.03475 (64)<br>
632 Obj 0.077664609 Primal inf 167.63095 (63)<br>
716 Obj 0.08533722 Primal inf 123.90711 (47)<br>
800 Obj 0.093453993 Primal inf 94.340415 (35)<br>
884 Obj 1.079625 Primal inf 0.56385768 (23)<br>
950 Obj 1.669254<br>
Optimal - objective value 1.5664076<br>
After Postsolve, objective 1.5664076, infeasibilities - dual 0 (0), primal 0 (0)<br>
Optimal objective 1.566407646 - 950 iterations time 0.112, Presolve 0.03<br>
<br>
<br>
<br>
Now, If I run cbc on this problem, it never stops.<br>
An example of the log I've got:<br>
<br>
Cbc0010I After 91600 nodes, 675 on tree, 1e+50 best solution, best possible 202 (1278.41 seconds)<br>
Cbc0010I After 91700 nodes, 626 on tree, 1e+50 best solution, best possible 202 (1279.79 seconds)<br>
Cbc0010I After 91800 nodes, 724 on tree, 1e+50 best solution, best possible 202 (1281.46 seconds)<br>
Cbc0010I After 91900 nodes, 805 on tree, 1e+50 best solution, best possible 202 (1283.06 seconds)<br>
Cbc0010I After 92000 nodes, 709 on tree, 1e+50 best solution, best possible 202 (1284.15 seconds)<br>
<br>
<br>
I feel the number of best solutions is quite strange: 1e+50 (this number never changes).<br>
<br>
I performed these tests on the trunk version of cbc. I will try the same test on an older version of cbc.<br>
<br>
Best regards,<br>
<br>
YC<br>
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