ILOG CPLEX 11.0 User's Manual

C H A P T E R31Goals and Callbacks: a ComparisonGoals and callbacks both provide an API within IloCplex to allow you to take control overthe branch & cut search for solving MIP models. With one exception, the same functionalityis available in both APIs. In fact, the goal API is built on top of callbacks. As a consequence,you cannot use callbacks and goals at the same time. To help you choose which API is moresuited to your needs, this section examines commonalities and differences between both.As pointed out previously, both APIs allow you to control the branch & cut search used byIloCplex to solve MIP models. The following points distinguish specific features of thiscontrol.◆◆◆Checking feasibility●●With goals, you can discontinue the search at a node by returning a Fail goal.Alternatively, you can continue searching, even though an integer feasible solution hasbeen found, by returning another nonempty goal.With callbacks, you can use method prune of the branch callback to discontinue thesearch, and an incumbent callback to accept or reject integer feasible solutions.Creating branches●●With goals, you create branches by using Or goals with local cut goals as parameters.With callbacks, you create branches by using a branch callback.Adding local or global cutsILOG CPLEX 11.0 — USER’ S MANUAL 469