Originally posted by: johncapon

Hello,

I have a doubt. I am solving the same problem (model) with cplex 12.
In C I obtain:

MIP Presolve eliminated 0 rows and 1074 columns

however with CPLEX C++ I obtain:

MIP Presolve eliminated 1235 rows and 1075 columns

Why I have this difference?

Thanks a lot!
#CPLEXOptimizers
#DecisionOptimization

Originally posted by: SystemAdmin

The presence of certain kinds of logical constraints in a model can lead to the creation of extra variables and constraints with Concert technology (including C++) as opposed to the use of the callable library (C). Per your node logs(MIP Presolve eliminated 1235 rows and 1075 columns) it looks like these extra constraints then get eliminated (resolved/fixed) during the presolve operations. You could go through the following documentation link and see if it is relevant for your model:

http://publib.boulder.ibm.com/infocenter/cosinfoc/v12r3/topic/ilog.odms.cplex.help/Content/Optimization/Documentation/Optimization_Studio/_pubskel/ps_usrmancplex1962.html
#CPLEXOptimizers
#DecisionOptimization