#22

(b) If, for every nonempty subset Bi of B, there exists a subset Ai of A such that f(A) B1, 22. For nonempty sets A, B and C, let f : A B and g: B C be functions. Prove that if go f 23. For nonempty sets A, B and C, let f:A B and g: B C be functions. Disprove each of then f is onto. is one-to-one, then f is one-to-one. the following