Why can't programs be proven?

Question

Why can\'t a computer program be proven just as a mathematical statement can? A mathematical proof is built up on other proofs, which are built up from yet more proofs and

Answer 1

Something that has not been mentioned here is the B - Method which is a formal method based system. It was used to develop the safety system of the Paris underground. There are tools available to support B and Event B development, notably Rodin.