Propositional logic
Propositional logic is a formal system in mathematics and logic. Other names for the system are propositional calculus and sentential calculus. The system is made of a set of propositions. Each proposition has a truth value, being either true or false. Propositions can be represented by capital roman letters such as ,  and , and joined together using logical connectives to make new propositions. Examples for logical connectives that are used often are logical and (), logical or (), logical if (), logical if and only if () and logical not ().