Permutations and combinations Permutations of sets combinations of sets circular permutation Permutations and Combinations of multisets Formulae o inclusion-exclusion principle generating functions integral solutions of the equation ◆ example, exercise2. Permutations and Combinations  Permutations of sets, Combinations of sets  circular permutation  Permutations and Combinations of multisets  Formulae  inclusion-exclusion principle  generating functions  integral solutions of the equation  example，exercise