# Math Help - Proofs: pigeonhole principle and functions

1. ## Proofs: pigeonhole principle and functions

I need help with two proofs.

First, I must prove the pigeon hole principle.

Second, Let f: A --> B be an injection between two finite sets of the same size. From this, Prove the f is a bijection.

2. Originally Posted by jzellt
I need help with two proofs.

First, I must prove the pigeon hole principle.
see here, or here

Second, Let f: A --> B be an injection between two finite sets of the same size. From this, Prove the f is a bijection.