1. The problem statement, all variables and given/known data N is the set of natural numbers, Z is the set of all integers Construct a function a : N -> Z that is both one to one and onto. Construct a function b : Z -> N that is one to one but not onto. 3. The attempt at a solution The only attempts have been very wrong - not even sure where to start since in both cases it doesn't seem that a solution is possible.