Solver hangs - No solution found this major pass

[masoudML]

Hi,

I have been working on an MILP and I have been getting "No solution found with major pass" and " Cbc0038I Before mini branch and bound, 2 integers at bound fixed and 22 continuous" (see below). The problem is the solver hangs and doesn't continue beyond this point. In some of the problematic runs (not all), when we increase the opt_tol to 1e-5 or 1e-4 it solves and finds the solution in the major pass. I am wondering if you can point out the possibilities for this so we can better find a solution to this problem. PS: we tried both mip==1.9.1 and 1.9.2.

Thanks!

Coin3007W ### CoinLpIO::checkRowNames(): non distinct or missing row names or objective function name. Now using default row names. Starting solution of the Linear programming relaxation problem using Dual Simplex

Coin0506I Presolve 65 (-50) rows, 68 (-23) columns and 164 (-85) elements Clp0014I Perturbing problem by 0.001% of 0.21756412 - largest nonzero change 0.0007721478 ( 49.251696%) - largest zero change 0.00076793457 Clp0006I 0 Obj 2.2586235 Primal inf 697.79762 (16) Dual inf 0.36188959 (5) Clp0000I Optimal - objective value -0.25526765 Coin0511I After Postsolve, objective -0.25526765, infeasibilities - dual 0 (0), primal 0 (0) Clp0032I Optimal objective -0.2552676458 - 22 iterations time 0.002, Presolve 0.00

Starting MIP optimization maxSavedSolutions was changed from 0 to 10 Continuous objective value is -0.255268 - 0.00 seconds Cgl0002I 3 variables fixed Cgl0003I 0 fixed, 0 tightened bounds, 7 strengthened rows, 0 substitutions Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions Cgl0004I processed model has 38 rows, 50 columns (9 integer (9 of which binary)) and 115 elements Coin3009W Conflict graph built in 0.000 seconds, density: 0.337% Cgl0015I Clique Strengthening extended 0 cliques, 0 were dominated Cbc0038I Initial state - 4 integers unsatisfied sum - 0.951873 Cbc0038I Pass 1: suminf. 0.00000 (0) obj. 0.064487 iterations 12 Cbc0038I Solution found of 0.064487 Cbc0038I Relaxing continuous gives 0.0644732 Cbc0038I Before mini branch and bound, 5 integers at bound fixed and 22 continuous Cbc0038I Full problem 38 rows 50 columns, reduced to 11 rows 13 columns Cbc0038I Mini branch and bound improved solution from 0.0644732 to -0.0974106 (0.01 seconds) Cbc0038I Round again with cutoff of -0.109617 Cbc0038I Pass 2: suminf. 0.51000 (3) obj. -0.109617 iterations 10 Cbc0038I Pass 3: suminf. 0.22318 (3) obj. -0.109617 iterations 11 Cbc0038I Pass 4: suminf. 0.06378 (2) obj. -0.109617 iterations 17 Cbc0038I Pass 5: suminf. 0.13146 (2) obj. -0.109617 iterations 7 Cbc0038I Pass 6: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 7: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 8: suminf. 0.89172 (4) obj. -0.109617 iterations 4 Cbc0038I Pass 9: suminf. 0.51159 (3) obj. -0.109617 iterations 1 Cbc0038I Pass 10: suminf. 0.51159 (3) obj. -0.109617 iterations 1 Cbc0038I Pass 11: suminf. 0.51159 (3) obj. -0.109617 iterations 1 Cbc0038I Pass 12: suminf. 0.06378 (2) obj. -0.109617 iterations 7 Cbc0038I Pass 13: suminf. 0.06378 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 14: suminf. 0.06378 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 15: suminf. 0.10998 (2) obj. -0.109617 iterations 7 Cbc0038I Pass 16: suminf. 0.22318 (3) obj. -0.109617 iterations 10 Cbc0038I Pass 17: suminf. 0.31479 (4) obj. -0.109617 iterations 1 Cbc0038I Pass 18: suminf. 0.31479 (4) obj. -0.109617 iterations 0 Cbc0038I Pass 19: suminf. 0.69492 (5) obj. -0.109617 iterations 3 Cbc0038I Pass 20: suminf. 0.06378 (2) obj. -0.109617 iterations 15 Cbc0038I Pass 21: suminf. 0.13146 (2) obj. -0.109617 iterations 7 Cbc0038I Pass 22: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 23: suminf. 0.51159 (3) obj. -0.109617 iterations 2 Cbc0038I Pass 24: suminf. 0.51159 (3) obj. -0.109617 iterations 0 Cbc0038I Pass 25: suminf. 0.51159 (3) obj. -0.109617 iterations 2 Cbc0038I Pass 26: suminf. 0.06378 (2) obj. -0.109617 iterations 7 Cbc0038I Pass 27: suminf. 0.13146 (2) obj. -0.109617 iterations 8 Cbc0038I Pass 28: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 29: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 30: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I Pass 31: suminf. 0.13146 (2) obj. -0.109617 iterations 0 Cbc0038I No solution found this major pass Cbc0038I Before mini branch and bound, 2 integers at bound fixed and 22 continuous

[h-g-s]

We can only debug if you provide us the data/code.

[sebheger]

I will close this issue, as no data/code was provided for nearly 2 years.