tailieunhanh - Lecture note Formal methods in software engineering - Lecture 5: Formal system (continue)

We have already defined the language and propositional formulas. To complete the formal system of propositional logic we need a set of axioms and inference rules. Why would we need a formal system? We are already able to construct well- formed formulas and decide on their truthfulness by means of a truth table. How- ever, imagine we had a set of formulas M and we know that they are true – they represent our knowledge about a certain problem. | .