4.I.1D
Part IA, 2008
Let and be non-empty sets and let and be two functions. For each of the following statements, give either a brief justification or a counterexample.
(i) If is an injection and is a surjection, then is a surjection.
(ii) If is an injection and is an injection, then there exists a function such that is equal to the identity function on .
(iii) If and are subsets of then .
(iv) If and are subsets of then .