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Advanced Counting Using PIE

The principle of inclusion-exclusion for overlapping "bad" cases, applied to distributions with a per-recipient cap.

Discrete Mathematics: An Open Introduction, Advanced Counting Using PIE

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1 exercise

Exercise 7

Illustrate how the counting of derangements works by writing all permutations of $\{1,2,3,4\}$ and the crossing out those which are not derangements. Keep track of the permutations you cross out more than once, using PIE.

2.5