ILOG CPLEX C++ API 9.0 Reference Manual

accepts the injected solution, it first tests whether the injected solution is feasible
with respect to the model and goals.
◆ When ILOG CPLEX executes any other goal, the returned goal is simply pushed
onto the stack.
IloCplex continues popping goals from the goal stack until OrGoal or FailGoal
is executed, or until the stack becomes empty; in the case of an empty stack, it will
continue with a built-in search strategy.
The predefined goals OrGoal and AndGoal allow you to combine goals. AndGoal
allows you to execute different goals at one node, while OrGoal allows you to execute
different goals on different, newly created nodes. A conventional use of these two goals
in a return statement of a user-written goal looks like this:
return AndGoal ( OrGoal (branch1, branch2), this);
This AndGoal first pushes this (the goal currently being executed) onto the goal
stack, and then it pushes the OrGoal. Thus the OrGoal is on top of the stack and will
be executed next. When the OrGoal executes, it creates two new nodes and copies the
remaining goal stack to both of them. Thus both new nodes will have this goal on top
of the goal stack at this point. Then the OrGoal proceeds to push branch1 onto the
goal stack of the first child node and branch2 onto the goal stack of the second goal
child node. Conventionally, branch1 and branch2 contain cut goals, so by
executing branch1 and branch2 at the respective child nodes, the child nodes will
be restricted to represent smaller subproblems than their parent. After branch1 and
branch2 have been executed, this is on top of the node stack of both child nodes;
that is, both child nodes will continue branching according to the same rule. In
summary, this example creates the branches branch1 and branch2 and continues in
both branches to control the same search strategy this.
To perform a search using a goal, you need to solve the extracted model by calling the
method IloCplex::solve(goal) with the goal to use as an argument instead of
the standard IloCplex::solve. The method solve(goal) simply pushes the
goal onto the goal stack of the root node before calling the standard solve.
See Also
IloCplex::Goal and IloCplex::GoalI
ILOG CPLEX C++ API 9.0 REFERENCE M ANUAL 11