I have a question in my homework for my math proof's class. Let S be a collection of n≥2 numerically equivalent sets. Prove that these sets can be shown to be numerically equivalent (same cardinality) by means of n-1 bijective functions between pairs of sets in S.
My problem here is the "n-1 bijective funtions" part. Does this mean that if S has two numerically equivalent sets, then there is at least one function between them?