Originally posted by: SystemAdmin

[leo said:]

hi, all,

I use cplex to implement the branch and cut.  In B&C, we use a cutcallback to add the cuts. I have turned off all other cuts routines by which cplex  can automatically added the cuts. And I also turn off the presolve and heuristic

At the root node, cplex can call cutcallback one time and add one cut. Then it should resolve the LP problem (in fact the solution is not integer) and call the cutcallback again.

But during my implementation, cplex stop after calling the cutcallback one time at root node. It shows:

Tried aggregator 0 times.
No MIP presolve or aggregator reductions.
Presolve time =    0.00 sec.
Clique table members: 4
MIP emphasis: balance optimality and feasibility
Root relaxation solution time =    0.00 sec.

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

      0    0      45.4545    7                    45.4545      30       

                infeasible                          User:  1      30       

User cuts applied: 1
Solution status 103.
CPLEX Error  3017: No integer feasible solution exists.
Failed to obtain objective value.


I do not know why the cplex stop. It should call the cutcallback to add more cut(in fact more cut be found). And the above information also shows branching is not implemented and cplex stop at root node.

Thanks.
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

[prubin said:]

The error message tells the tale.  CPLEX concluded at the root node that the problem has no integer feasible solutions.  Adding cuts cannot make an infeasible problem feasible, so CPLEX (correctly) stops.  Check your cut and make sure it does not make the problem infeasible (counting the integrality restrictions -- the LP relaxation may still be feasible).

/Paul
#CPLEXOptimizers
#DecisionOptimization