Originally posted by: BhavnaJha

Hi, 

I have a large CPLEX model, and when I solve it, I get no solution. I can't figure out what is causing the infeasibility because it doesn't tell which constraint is causing it. 

This is what the log looks like.

<<< setup

<<< generate

Tried aggregator 2 times.
MIP Presolve eliminated 139828 rows and 7185639 columns.
MIP Presolve modified 2448 coefficients.
Aggregator did 92 substitutions.
Reduced MIP has 6523 rows, 1814564 columns, and 5723880 nonzeros.
Reduced MIP has 0 binaries, 612 generals, 0 SOSs, and 0 indicators.
Presolve time = 31.11 sec. (6869.39 ticks)
Tried aggregator 1 time.
MIP Presolve eliminated 6 rows and 5439 columns.
Reduced MIP has 6517 rows, 1809125 columns, and 5709330 nonzeros.
Reduced MIP has 0 binaries, 612 generals, 0 SOSs, and 0 indicators.
Presolve time = 9.05 sec. (1987.67 ticks)
MIP emphasis: balance optimality and feasibility.
MIP search method: dynamic search.
Parallel mode: deterministic, using up to 4 threads.
Root relaxation solution time = 487.45 sec. (270530.28 ticks)

        Nodes                                         Cuts/
   Node  Left     Objective  IInf  Best Integer    Best Bound    ItCnt     Gap

      0     0    infeasible                                      56722         

Root node processing (before b&c):
  Real time             =  535.95 sec. (282052.24 ticks)
Parallel b&c, 4 threads:
  Real time             =    0.00 sec. (0.00 ticks)
  Sync time (average)   =    0.00 sec.
  Wait time (average)   =    0.00 sec.
                          ------------
Total (root+branch&cut) =  535.95 sec. (282052.24 ticks)

<<< solve

<<< no solution

Please help ASAP. 

Thank you. 

Hi

label your constraint and then the infeasibility analysis tool will give you some relaxation.

https://www.youtube.com/watch?v=tUALbhJ2xWY

regards

Originally posted by: BhavnaJha

I have labeled all my constraints. But still the it's not giving the constraint which is causing infeasibility. 

I'm running my program in OPLRun.exe directly. How to use the infeasibility analysis there through opl?  

Hi,

 -relax              calculate relaxations needed to get
                       a feasible model, CPLEX only
 -conflict           calculate a conflict for
                       an infeasible model

oplrun -relax model.mod data.dat

regards

Originally posted by: BhavnaJha

How to do I implement in this in the ILOG CPLEX OPTIMIZATION Studio code?  

There is nothing to implement in the code. You just give command line option '-conflict' to oplrun.exe.