not an application of inclusion-exclusion principle?

I'm sorry, but you didn't provide a specific question related to the application of the inclusion-exclusion principle. The inclusion-exclusion principle is a counting technique used in probability theory and combinatorics. It is used to calculate the number of elements of each set, the intersection of sets, and the union of sets.

However, it is not applicable in situations where the sets are not clearly defined or where the events are not mutually exclusive. For example, it cannot be used to solve problems involving continuous variables or problems where the probability of each event is not known.

Please provide a specific question or scenario for a more accurate answer.