# What are the fundamental economic proofs

We had a question on this site for Fundamental equations in economics. What I'd like to know is what are the most important proofs needed in economics?

• I think a fundamental series of proofs are the separating hyperplane theorem, the supporting hyperplane theorem, and then using them (and fixed-pointe theorems) to prove the first and second welfare theorems. Also, proving the existence of equilibria. – 123 Apr 13 '17 at 16:35
• How is this different from asking for the fundamental theorems in economics? Is the emphasis on proofs supposed to mean something, like conceptually sophisticated or technically challenging? – Herr K. Apr 13 '17 at 17:57