 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2016/discrete-mathematics-continuous-mathematics-and-probability/2/b/i/solution

Using the wiki convention that paths follow the written order of the binary relations, composition of relations is

R \circ S = {(x, z) \in A \times A : \exists y \in A, (x, y) \in R and (y, z) \in S} .

Some treatments reverse the naming convention; stating it explicitly avoids ambiguity. The powers of the single relation

R

below are the same under either convention.

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