Suppose A = {a1, . . . , am} and B = {b1, . . . , bn}. Let R and T be relations from A to B with matrices M and N respectively. How is the matrix of R ∪ T obtained from M and N? How about the matrix of R ∩ T? Suppose C is a non-empty set and that T is a relation from B to C. We define the composite relation R ◦ T from A to C by declaring aTc if there is b ∈ B such that aRb and bRc.