This callback is called whenever a new potential incumbent is found during branch-and-cut searches. It allows you to analyze the proposed incumbent and optionally reject it. In this case, CPLEX will continue the branch-and-cut search. This callback is thus typically combined with a branch callback that instructs CPLEX how to branch on a node after it has found a potential incumbent and thus considered the node solution to be integer feasible.

When you use this callback to reject an incumbent, you must also set the parameter to control type of primal and dual reductions, IloCplex::Reduce either to 1 (one) in order to restrict presolve to primal reductions only, or to 0 (zero) in order to disable all presolve reductions. This setting of the reduction parameter is not necessary if the incumbent callback is used for other purposes.

This method retrieves the NodeData object that may have previously been assigned to the current node by the user with the method IloCplex::BranchCallbackI::makeBranch. If no data object has been assigned to the current node, 0 (zero) will be returned.

This method returns the NodeId of the current node.

See MIPCallbackI::NodeId.

This method returns the query objective value of the potential incumbent.

If you need the object representing the objective itself, consider the method IloCplex::getObjective instead.

This method returns the slack value for the range specified by rng for the potential incumbent.

This method puts the slack value for each range in the array of ranges con into the corresponding element of the array val for the potential incumbent. For this CPLEX resizes array val to match the size of array con.

This method returns the source of the solution for which the callback was invoked.

This method returns the query value of the variable var in the potential incumbent solution.

For special considerations about integrality, truncation, and rounding applicable to this method, see the concept Integer values, integrality tolerance, and round-off in CPLEX Optimizers.

This method returns the value of the variable var in the potential incumbent solution.

This method returns the value of the expr for the potential incumbent solution.

This method returns the query values of the variables in the array vars in the potential incumbent solution and copies them to val. CPLEX automatically resizes the array val to match the size of the array vars.

For special considerations about integrality, truncation, and rounding applicable to this method, see the concept Integer values, integrality tolerance, and round-off in CPLEX Optimizers.

This method returns the query values of the variables in the array vars in the potential incumbent solution and copies them to val. CPLEX automatically resizes the array val to match the length of the array vars.

This method rejects the proposed incumbent.

This method sets the NodeData object assigned to the the current node. If a NodeData object has already been set for the current node, then the method replaces this object and and returns the old object. Otherwise, the method returns 0 (zero).

This method returns the callback type of the invoking callback object.

This enumeration lists the values that tell for which type of solution the incumbent callback or lazy constraint callback was invoked.

• NodeSolution The integral solution was found as the solution to an LP-relaxation of a node in the search tree.
• HeuristicSolution The integral solution was found by a CPLEX internal heuristic.
• UserSolution The integral solution was found by the user's heuristic callback function. This value is returned only in incumbent callbacks, not in lazy constraint callbacks.
• MIPStartSolution The integral solution was found during MIP start processing. Note that callbacks invoked in this situation do not have the full API available. For example, you cannot set/get user data to a node, nor can you do anything else that requires a search tree node context.