Definition
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[00D]A propositional logic is a language, with associated an alphabet of variables (which for convenience in the following we will identify with the Italian alphabet) and a family of connectives 1
\begin{align*} \text{negation, NOT} & & ¬ \\ \text{conjunction, AND} & & { ∧ } \\ \text{disjunction, OR} & & { ∨ } \\ \text{implication} & & ⇒ \\ \text{biconditional, iff} & & ⇔ \end{align*}
to these symbols we add parentheses, which are used to group parts of the formula (when there is a risk of ambiguity); the parentheses are omitted when the precedence of the operators allows; the operators are listed in the previous list in descending order of precedence. 2