[[Logic MOC]]
# Formal language

A **formal language** $\mathcal{L}$ with an alphabet $A$ is a set of strings in the alphabet $A$,
i.e. a subset of the [[free monoid]] $A^*$. #m/def/logic
The strings in $\mathcal{L}$ are called **well-formed formulae** or just **formulae** of $\mathcal{L}$.
Usually there is an [[effective procedure]] for determining if a given string is a formula of $\mathcal{L}$,
e.g. as defined by a [[formal grammar]].

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#state/develop | #lang/en | #SemBr