Definition:Structure for Predicate Logic

Definition
Let $\mathcal L_1$ be the predicate calculus.

A structure $\mathcal A$ for $\mathcal L_1$ comprises:


 * $(1):$ A non-empty set $A$;
 * $(2):$ For each function symbol $f$ of arity $n$, a mapping $f_{\mathcal A}: A^n \to A$;
 * $(3):$ For each predicate symbol $p$ of arity $n$, a mapping $p_{\mathcal A}: A^n \to \Bbb B$

where $\Bbb B$ denotes the set of truth values.

We remark that function symbols of arity $0$ are interpreted as constants in $A$.

Also, the predicate symbols may be interpreted as relations via their characteristic functions.

Also see

 * Definition:Predicate Calculus
 * Definition:Structure (Formal Systems)