I tried to run the file <a href="http://www.dei.unipd.it/~fisch/knuth_corrected.lp">http://www.dei.unipd.it/~fisch/knuth_corrected.lp</a> through cbc version 2.7.5 both on my Redhat Linux system at work and my macbook running Mountain Lion at home. In both cases I built it from the latest source (as part of CoinAll). First, cbc is a little more picky than, say glpk, in that it didn't like the input. It took me a while (since the error messages didn't specify a line number where it thought that there was an error!) to correct it by inserting white space in between coefficients and variable names and in between >= and the value on the right hand side. However, once I gave the corrected version to cbc, it eventually segment faulted. This is definitely a bug! Here's the output from my Linux system.<br>
<br>Victor<br><br>cbc knuth_corrected.lp<br>Welcome to the CBC MILP Solver <br>Version: 2.7.5 <br>Build Date: Sep 10 2012 <br><br>command line - cbc knuth_corrected.lp (default strategy 1)<br>
Continuous objective value is 13793 - 0.00 seconds <br>Cgl0003I 0 fixed, 52 tightened bounds, 0 strengthened rows, 0 substitutions<br>Cgl0004I processed model has 44 rows, 52 columns (52 integer) and 149 elements<br>
Objective coefficients multiple of 2 <br>Cutoff increment increased from 1e-05 to 1.998 <br>Cbc0031I 16 added rows had average density of 16.3125 <br>
Cbc0013I At root node, 16 cuts changed objective from 14277 to 18872.054 in 100 passes <br>Cbc0014I Cut generator 0 (Probing) - 0 row cuts average 0.0 elements, 6 column cuts (6 active) in 0.009 seconds - new frequency is 1 <br>
Cbc0014I Cut generator 1 (Gomory) - 1721 row cuts average 25.2 elements, 0 column cuts (16 active) in 0.032 seconds - new frequency is 1 <br>Cbc0014I Cut generator 2 (Knapsack) - 0 row cuts average 0.0 elements, 0 column cuts (0 active) in 0.011 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) - 38 row cuts average 3.0 elements, 0 column cuts (0 active) in 0.005 seconds - new frequency is -100 <br>
Cbc0014I Cut generator 5 (FlowCover) - 0 row cuts average 0.0 elements, 0 column cuts (0 active) in 0.007 seconds - new frequency is -100 <br>Cbc0014I Cut generator 6 (TwoMirCuts) - 303 row cuts average 7.2 elements, 0 column cuts (0 active) in 0.014 seconds - new frequency is -100 <br>
Cbc0010I After 0 nodes, 1 on tree, 1e+50 best solution, best possible 18872.054 (0.16 seconds) <br>Cbc0012I Integer solution of 27646 found by rounding after 13872 iterations and 123 nodes (1.35 seconds) <br>
Cbc0038I Full problem 44 rows 52 columns, reduced to 3 rows 4 columns <br>Cbc0012I Integer solution of 27546 found by RINS after 13872 iterations and 123 nodes (1.35 seconds) <br>
Cbc0038I Full problem 44 rows 52 columns, reduced to 43 rows 46 columns <br>Cbc0012I Integer solution of 23196 found by combine solutions after 13872 iterations and 123 nodes (1.57 seconds) <br>
Cbc0012I Integer solution of 23096 found by combine solutions after 13954 iterations and 124 nodes (1.57 seconds) <br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 41 columns <br>
Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 41 columns <br>Cbc0012I Integer solution of 22996 found by RINS after 25086 iterations and 518 nodes (3.38 seconds) <br>
Cbc0038I Full problem 44 rows 52 columns, reduced to 34 rows 37 columns <br>Cbc0010I After 1000 nodes, 94 on tree, 22996 best solution, best possible 21301.043 (7.26 seconds) <br>
Cbc0038I Full problem 44 rows 52 columns, reduced to 37 rows 40 columns <br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 40 columns <br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 38 columns <br>
Cbc0038I Full problem 44 rows 52 columns, reduced to 38 rows 38 columns <br>Cbc0010I After 2000 nodes, 79 on tree, 22996 best solution, best possible 21480.243 (13.75 seconds)<br>Cbc0038I Full problem 44 rows 52 columns, reduced to 32 rows 31 columns<br>
Cbc0010I After 3000 nodes, 64 on tree, 22996 best solution, best possible 21480.243 (15.80 seconds)<br>Cbc0010I After 4000 nodes, 48 on tree, 22996 best solution, best possible 21480.243 (17.54 seconds)<br>Cbc0010I After 5000 nodes, 50 on tree, 22996 best solution, best possible 21480.243 (19.59 seconds)<br>
Cbc0010I After 6000 nodes, 46 on tree, 22996 best solution, best possible 21503.428 (21.50 seconds)<br>Cbc0010I After 7000 nodes, 54 on tree, 22996 best solution, best possible 21503.428 (23.06 seconds)<br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 40 columns<br>
Cbc0010I After 8000 nodes, 53 on tree, 22996 best solution, best possible 21503.428 (24.77 seconds)<br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 40 columns<br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 38 columns<br>
Cbc0010I After 9000 nodes, 45 on tree, 22996 best solution, best possible 21503.428 (26.55 seconds)<br>Cbc0038I Full problem 44 rows 52 columns, reduced to 41 rows 39 columns<br>Cbc0010I After 10000 nodes, 50 on tree, 22996 best solution, best possible 21503.428 (28.31 seconds)<br>
Cbc0010I After 11000 nodes, 44 on tree, 22996 best solution, best possible 21747.031 (30.30 seconds)<br>Segmentation fault (core dumped)<br><br>