# Show infeasibilities in MILP

Question asked by rlopeznegrete on Apr 20, 2018
Latest reply on Apr 23, 2018 by timoberthold@fico.com

Hi all,

I'm trying to solve an MILP, but the model is not feasible. The solver is returning with the messages below. I'm trying to figure out which constraints are the culprits, but I'm unable to find out using 'getinfeas', 'getinfeascause', or 'getiis'. All three methods return empty in all cases. Is there something I'm missing? How else can I get the information about which constraints are not feasible?

thank you,

Rodrigo

solver log:

Problem Statistics

3653 (      0 spare) rows

2686 (      0 spare) structural columns

17900 (      0 spare) non-zero elements

Global Statistics

1060 entities        0 sets        0 set members

Minimizing MILP \xprs_71cd4c80

Original problem has:

3653 rows         2686 cols        17900 elements      1060 globals

Will try to keep branch and bound tree memory usage below 22.2Gb

Starting concurrent solve with dual, primal and barrier (6 threads)

Concurrent-Solve,   1s

Dual                      Primal                     Barrier

objective   sum inf

|                          |  P  18821.000   .0000000

----- interrupted ------ | ----- interrupted ------ | ------- optimal --------

Concurrent statistics:

Dual: 1370 simplex iterations, 0.08s

Primal: 1370 simplex iterations, 0.02s

Barrier: 31 barrier and 717 simplex iterations, 0.23s

Barrier used 6 threads 4 cores, L1\L2 cache: 32K\8192K

Barrier used AVX support

Optimal solution found

Its         Obj Value      S   Ninf  Nneg        Sum Inf  Time

0       18820.99994      P      0     0        .000000     1

Barrier solved problem

31 barrier iterations in 1s

Final objective                         : 1.882099994400000e+04

Max primal violation      (abs / rel) :       0.0 /       0.0

Max dual violation        (abs / rel) : 9.095e-13 / 7.276e-13

Max complementarity viol. (abs / rel) :       0.0 /       0.0

All values within tolerances

Starting root cutting & heuristics

Deterministic mode with up to 8 running threads and up to 16 tasks.

Its Type    BestSoln    BestBound   Sols    Add    Del     Gap     GInf   Time

*** Search completed ***     Time:     1 Nodes:          1

Problem is integer infeasible

Number of integer feasible solutions found is 0

Best bound is  18820.99994