Wrong result for ILP, regression in the last 1 or 2 months

[christoph-cullmann]

See the attached ILP value_3810812.lp.gz

I updated my local CBC to current master (including osi,coinutils,...), now cbc computes a different result (mismatching the cplex one)

❯ ../usr/bin/cbc /local/ssd/cullmann/build/lpsolve.clpsolve/lpsolve.clpsolve/test/value_3810812.lp
Welcome to the CBC MILP Solver
Version: trunk
Build Date: Aug 27 2024
command line - /local/ssd/cullmann/build/lpsolve.clpsolve/lpsolve.clpsolve/test/value_3810812.lp (default strategy 1)
 CoinLpIO::readLp(): Maximization problem reformulated as minimization
Problem value_3810812.lp has 323252 rows, 345638 columns and 779275 elements
Coin0009I Switching back to maximization to get correct duals etc
Continuous objective value is 3.81114e+06 - 1.1533 seconds
Cgl0003I 0 fixed, 429 tightened bounds, 24 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 134 tightened bounds, 19 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 16 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 9 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0004I processed model has 632 rows, 5585 columns (5585 integer (3563 of which binary)) and 11494 elements
Coin3009W Conflict graph built in 0.001 seconds, density: 0.050%
Cgl0015I Clique Strengthening extended 0 cliques, 0 were dominated
Cbc0038I Initial state - 78 integers unsatisfied sum - 24.8557
Cbc0038I Solution found of 3.81106e+06
Cbc0038I Branch and bound needed to clear up 78 general integers
Cbc0038I Full problem 632 rows 5585 columns, reduced to 289 rows 1982 columns
Cbc0038I Cleaned solution of 3.8108e+06
Cbc0038I Before mini branch and bound, 5507 integers at bound fixed and 0 continuous of which 167 were internal integer and 0 internal continuous
Cbc0038I Mini branch and bound did not improve solution (3.06 seconds)
Cbc0038I Round again with cutoff of 3.81082e+06
Cbc0038I Reduced cost fixing fixed 309 variables on major pass 2
Cbc0038I Solution found of 3.81106e+06
Cbc0038I Branch and bound needed to clear up 78 general integers
Cbc0038I Full problem 633 rows 5585 columns, reduced to 247 rows 1859 columns
Cbc0038I Mini branch and bound could not fix general integers
Cbc0038I No solution found this major pass
Cbc0038I Before mini branch and bound, 5507 integers at bound fixed and 0 continuous of which 167 were internal integer and 0 internal continuous
Cbc0038I Mini branch and bound did not improve solution (3.30 seconds)
Cbc0038I After 3.31 seconds - Feasibility pump exiting with objective of 3.8108e+06 - took 0.62 seconds
Cbc0012I Integer solution of 3810796 found by feasibility pump after 0 iterations and 0 nodes (3.31 seconds)
Cbc0038I Full problem 632 rows 5585 columns, reduced to 69 rows 103 columns
Cbc0012I Integer solution of 3810807 found by RINS after 0 iterations and 0 nodes (3.46 seconds)
Cbc0031I 41 added rows had average density of 6.0243902
Cbc0013I At root node, 196 cuts changed objective from 3811056 to 3810811.7 in 9 passes
Cbc0014I Cut generator 0 (Probing) - 8 row cuts average 4.4 elements, 38 column cuts (68 active)  in 0.116 seconds - new frequency is 1
Cbc0014I Cut generator 1 (Gomory) - 133 row cuts average 6.4 elements, 0 column cuts (0 active)  in 0.006 seconds - new frequency is 1
Cbc0014I Cut generator 2 (Knapsack) - 0 row cuts average 0.0 elements, 0 column cuts (0 active)  in 0.002 seconds - new frequency is -100
Cbc0014I Cut generator 3 (Clique) - 953 row cuts average 2.0 elements, 0 column cuts (0 active)  in 0.011 seconds - new frequency is 1
Cbc0014I Cut generator 4 (OddWheel) - 0 row cuts average 0.0 elements, 0 column cuts (0 active)  in 0.008 seconds - new frequency is -100
Cbc0014I Cut generator 5 (MixedIntegerRounding2) - 0 row cuts average 0.0 elements, 0 column cuts (0 active)  in 0.099 seconds - new frequency is -100
Cbc0014I Cut generator 6 (FlowCover) - 0 row cuts average 0.0 elements, 0 column cuts (0 active)  in 0.001 seconds - new frequency is -100
Cbc0014I Cut generator 7 (TwoMirCuts) - 287 row cuts average 6.7 elements, 0 column cuts (0 active)  in 0.009 seconds - new frequency is -100
Cbc0014I Cut generator 8 (ZeroHalf) - 13 row cuts average 5.8 elements, 0 column cuts (0 active)  in 0.007 seconds - new frequency is -100
Cbc0001I Search completed - best objective 3810807, took 219 iterations and 0 nodes (3.75 seconds)
Cbc0035I Maximum depth 0, 318 variables fixed on reduced cost
Cuts at root node changed objective from 3.81106e+06 to 3.81081e+06
Probing was tried 9 times and created 46 cuts (0.11636 seconds)
Gomory was tried 9 times and created 133 cuts (0.006054 seconds)
Knapsack was tried 9 times and created 0 cuts (0.002253 seconds)
Clique was tried 9 times and created 953 cuts (0.01117 seconds)
OddWheel was tried 9 times and created 0 cuts (0.008488 seconds)
MixedIntegerRounding2 was tried 9 times and created 0 cuts (0.099061 seconds)
FlowCover was tried 9 times and created 0 cuts (0.001188 seconds)
TwoMirCuts was tried 9 times and created 287 cuts (0.008898 seconds)
ZeroHalf was tried 9 times and created 13 cuts (0.006659 seconds)

Result - Optimal solution found
Objective value:                3810807
Enumerated nodes:               0
Total iterations:               219
Time (CPU seconds):             4.29664
Time (Wallclock seconds):       4.66537
Total time (CPU seconds):       4.95365   (Wallclock seconds):       5.37705