Problem III.4 Prove the following statements about functions: 1. The function () for E N is injective, but not surjective. 2. The constant function f(x) - c for N is not injective or surjective. 3. The inverse of a bijective function is bijective. 4. The composition of two bijective functions is bijective The proofs are somewhat involved using Coq, so students may prove them by hand