Assume that f : \mathbb{n} → \mathbb{n} and defined by f(n) = n - 1 for all n > 0 and f(0) = 0.
prove in this case that the function g : p(\mathbb{n}) → p(\mathbb{n}) is injective.
describe the sets g[{0,1,}], g[\mathbb{n}] and g[\mathbb{n} \ {0}].
is the function g surjective? show why.