 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2022/discrete-mathematics-continuous-mathematics-and-probability/discrete-mathematics/1/c/i/solution

i = 1 ⋃ n A_{i} = \emptyset \neq = J \subseteq {1, \dots, n} \sum (- 1)^{∣ J ∣ + 1} j \in J ⋂ A_{j} .

Thus single-set cardinalities are added, pairwise-intersection cardinalities subtracted, triple-intersection cardinalities added, and so on.

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