ILOG CPLEX 11.0 User's Manual

C H A P T E R33Advanced MIP Control InterfaceIn this manual, Using Optimization Callbacks on page 445 introduces callbacks, theirpurpose, and conventions. This chapter documents the CPLEX advanced MIP controlinterface, describing control callbacks in greater detail. It assumes that you are alreadyfamiliar with that introduction to callbacks in general, and it includes sections about:◆ Introduction to MIP Control Callbacks on page 484◆ Heuristic Callback on page 485◆ Cut Callback on page 487◆ Branch Selection Callback on page 488◆ Incumbent Callback on page 489◆ Node Selection Callback on page 489◆ Solve Callback on page 490These callbacks allow sophisticated users to control the details of the branch & cut process.Specifically, users can choose the next node to explore, choose the branching variable, addtheir own cutting planes, place additional restrictions on integer solutions, or insert their ownheuristic solutions. These functions are meant for situations where other tactics to improveCPLEX performance on a hard MIP problem, such as non-default parameter settings orpriority orders, have failed. See Troubleshooting MIP Performance Problems on page 288for more information about MIP parameters and priority orders.ILOG CPLEX 11.0 — USER’ S MANUAL 483