\begin{definition}[Definition:Propositional Logic]
'''Propositional logic''' is a sub-branch of symbolic logic in which the truth values of propositional formulas are investigated and analysed.
The atoms of propositional logic are simple statements.
There are various systems of propositional logic for determining the truth values of propositional formulas, for example:
* Natural deduction is a technique for deducing valid sequents from other valid sequents by applying precisely defined proof rules, each of which themselves are either "self-evident" axioms or themselves derived from other valid sequents.
* The Method of Truth Tables, which consists of the construction of one or more truth tables which exhaustively list all the possible truth values of all the statement variables with a view to determining the required answer by inspection.
\end{definition}