Example: Determine the number of 10-combinations of multiset s={3·a,4·b,5c} Solution: We shall apply the inclusion-exclusion principle to the set y of all 10-combinations of the multiset D=(oo.a b,o·c} Let p, be the property that a 10-combination of D has more than 3 as Let P2 be the property that a 10-combination of D has mote than 4 b's Let p3 be the property that a 10 combination of d has mote than 5c's Fori=1, 2, 3 let a i be the set consisting of those 10 combinations of d which have property P The number of 10-combinations of s is then the number of 10-combinations of D which have none of the properties p1, P. and p ∩A2∩▪ Example: Determine the number of 10-combinations of multiset S={3·a,4·b,5·c}. ▪ Solution：We shall apply the inclusion-exclusion principle to the set Y of all 10-combinations of the multiset D={·a, ·b, ·c}. ▪ Let P1 be the property that a 10-combination of D has more than 3 a’s. Let P2 be the property that a 10-combination of D has mote than 4 b’s. Let P3 be the property that a 10- combination of D has mote than 5 c’s. ▪ For i=1,2,3 let Ai be the set consisting of those 10- combinations of D which have property Pi . ▪ The number of 10-combinations of S is then the number of 10-combinations of D which have none of the properties P1 , P2 , and P3 . A1  A2  A3