Solving subproblems

Describes the parameters to control solution of subproblems.

CPLEX allows you to distinguish the algorithm applied to the initial relaxation of your problem from the algorithm applied to other continuous subproblems of a MIP. This distinction between initial relaxation and the other MIP subproblems may be useful when you have special information about the nature of your model. In this context, "other MIP subproblems" includes nodes of the branch & cut tree, problems re-solved after cutting plane passes, problems solved by node heuristics, and so forth.

The algorithm for initial MIP relaxation parameter (RootAlg, CPX_PARAM_STARTALG) enables you to specify which algorithm for CPLEX to apply to the initial relaxation.

The MIP subproblem algorithm parameter (NodeAlg, CPX_PARAM_SUBALG) lets you specify the algorithm applied to other continuous subproblems.

For more detail about situations in which you may find these parameters helpful, see Unsatisfactory optimization of subproblems.