1. The principle of optimality (Markovian property) should hold in a problem in order to be solved by _________.
2. The transportation problem is a special case of the __________.
3. A tree is a special case of a __________.
4. The __________ is a generalization of the assignment problem.
5. In any integer basic feasible solution of the _________, the number of positive variables is equal to half the number of functional constraints.