## Post without words #18

Assistant Professor of Computer Science at Hendrix College. Functional programmer, mathematician, teacher, pianist, follower of Jesus.
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### 5 Responses to Post without words #18

1. Prabhakar says:

That is one of the most beautiful descriptions of the Inclusion Exclusion Principle I’ve ever seen!

Really neat ! $P\left(\bigcup_{i=1}^n A_i \right) = \sum_{k=1}^n (-1)^{k-1} \sum_{1\leq i_1 < \dots < i_k\leq n} P\left(\bigcap_{j=1}^k A_{i_j}\right)$