(isPrefix.1) isPrefix([], B) = true (isPrefix.2) isPrefix(A, []) = false (when A is not []) (isPrefix.3) isPrefix(h1:t1, h2:t2) = h1 == h2 and isPrefix(t1, t2)Evaluation is as follows.
isPrefix([2,3,4], [2,4,3]) = isPrefix(2:[3,4], 2:[4,3]) = 2 == 2 and isPrefix([3,4], [4,3]) by (isPrefix.3) = true and isPrefix([3,4], [4,3]) = isPrefix([3,4], [4,3]) = isPrefix(3:[4], 4:[3]) = 3 ==4 and isPrefix([4], [3]) by (isPrefix.3) = false and isPrefix([4], [3]) = false