  There are several finite axiomatizations of stratified comprehension. The
famous two are Hailperin's and Randall Holmes's. However, the system presented
here could be the shortest known one written in the first order language of set
theory. This axiomatization uses unordered pairs, unlike the prior
axiomaizations which used ordered pairs, so this makes a simpler formulation in
the first order language of set theory. The proof works under absence of
Extensionality, so it can serve to complete an axiomatization of NFU or NF.
