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This is the problem:
"Prove that if A is denumerable and there exists a g: A -> B that is surjective, then there exists an h: B -> A so that h is injective."
So I've started it as:
Suppose a set A is denumerable and a function f: A-> B is surjective. Since there exists a surjective function f: A-> B and A is denumerable, B is countable..."
I'm a little stuck here. Any ideas?
"Prove that if A is denumerable and there exists a g: A -> B that is surjective, then there exists an h: B -> A so that h is injective."
So I've started it as:
Suppose a set A is denumerable and a function f: A-> B is surjective. Since there exists a surjective function f: A-> B and A is denumerable, B is countable..."
I'm a little stuck here. Any ideas?