This function creates and returns a search selector that implements a minimization search for the variable v.

The search selector that this function creates and returns does several things:

• It stores the leaf of the search tree corresponding to the optimal value of the variable v and then reactivates this variable after the complete exploration of the search tree defined by the goal passed to IloSelectSearch.
• It manages the upper bound on the objective variable. As soon as a solution of value d is found, the constraint v <= d - step is added to the solver for the remainder of the search tree.
• Open nodes are evaluated. The evaluation of an open node is equal to the current minimum of the variable v when the node is created. When the solver asks for an open node, it checks whether the current upper bound on the objective is less than the evaluation of the node. If so, the node is safely discarded.