 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2018/discrete-mathematics-continuous-mathematics-and-probability/1/c/i/solution

True. Fix

a \in A

. Reflexivity supplies

a R_{1} a

and

a R_{2} a

. In the definition of composition of relations, choose the intermediate element to be

a

itself. Then

a (R_{2} \circ R_{1}) a

. This holds for every

a \in A

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