Question:Let A, B, C be sets and let f : A → B and g :...
Question
Let A, B, C be sets and let f : A → B and g :...
Let A, B, C be sets and let f : A → B and g : f (A) → C be
one-to-one functions. Prove that their composition g ◦ f , defined
by g ◦ f (x) = g(f (x)), is also one-to-one.