n. (Logic) 1. a symbol of predicate calculus that contains a variable and indicates the generality of the open sentence in which that variable occurs. In particular, the existential quantifier is written (∃x), as in (∃x)Fx, and is rendered there exists an F, something Fs, Fs exist, or something is an F. The universal quantifier is written (x) by logicians and (∀ x) by mathematicians, as in (x)Fx or (∀x)Fx, and is rendered everything Fs or everything is an F. In a semantic interpretation of quantified formulae, it is necessary to specify a range of quantification. For example, is read `for all real x, x² ≥ 0'; this would be written by logicians as any analogous symbol in an extended logic, such as (Mx)Fx for most x are F, or restricted quantifiers such as (x : Fx)Gx for all Fs are Gs. See also numerical quantifier.