I'm confused. Two finite sets (call them A = [a, b] and C = [c, d]) are equivalent if there exists a 1-1 bijection from A to C. But the bijection exists iff A has the same number of elements as C.
So am I correct in saying that two finite sets can't be equivalent unless they have the same number of elements?
I've been asked this: Let a < b and c < d. Show [a, b] is equivalent to [c, d].