Finitely Axiomatized Set Theory: a nonstandard first-order theory implying ZF

It is well-known that a finite axiomatization of Zermelo-Fraenkel set theory (ZF) is not possible in the same first-order language. In this note we show that a finite axiomatization is possible if we extent the language of ZF with the new logical concept of `universal quantification over a family of variables indexed in an arbitrary set X'. We axiomatically introduce Finitely Axiomatized Set Theory (FAST), which consists of ten theorems of ZF plus a new constructive axiom called the family set axiom (FAM), the latter is a generalization of the pair axiom of ZF, which uses the new concept of quantification. We prove that FAM enables to derive the axioms schemes of separation and substitution of ZF from FAST, and that the L\"owenheim-Skolem theorem does not hold for FAST. The conclusions are (i) that FAST is a finite, nonstandard first-order theory, and (ii) that FAST implies ZF, but without the possibility of having a countable model.