for "A" an "L"-structure (or "L"-model) in a language "L", "φ" an "L"-formula, and formula_2 a tuple of elements of the domain dom("A") of "A". In other words, formula_3 denotes a (monadic) property defined on dom(A). In general, where "x" is replaced by an "n"-tuple formula_4 of free variables, formula_5 denotes an "n"-ary relation defined on dom("A"). Each quantifier formula_6 is relativized to a structure, since each quantifier is viewed as a family of relations (between relations) on that structure. For a concrete example, take the universal and existential quantifiers ∀ and ∃, respectively. Their truth conditions can be specified as