Inclusion-Exclusion principle
Inclusion-Exclusion and its various Applications Difficulty Level : Easy Last Updated : 17 Aug, 2021 Read Discuss In the field of Combinatorics, it is a counting method used to compute the cardinality of the union set. According to basic Inclusion-Exclusion principle : For 2 finite sets and , which are subsets of Universal set, then and are disjoint sets. Hence it can be said that, . Similarly for 3 finite sets , and , Principle : Inclusion-Exclusion principle says that for any number of finite sets , Union of the sets is given by = Sum of sizes of all single sets – Sum of all 2-set intersections + Sum of all the 3-set intersections – Sum of all 4-set intersections .. + Sum of all the i-set intersections. In general it can be said that, Properties : Computes the total number of elements that satisfy at least one of several properti...