Definition: Signature

In a logical calculus, a signature \(\Sigma\) is a triple \((V_\Sigma,F_\Sigma,P_\Sigma)\) of the following sets:

Every function \(f\in F_\Sigma\) has an arity $n\ge 0$, while for $n=0$ we call the functions constants.

Every predicate \(p\in P_\Sigma\) has an arity \(n\ge 1\).

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