ZF*-Extensionality interprets full ZF
Zuhair A. Al-Johar · arXiv (Cornell University) · 2020
Dana Scott had shown that removing Extensionality from ZF set theory formalized in the customary manner would weaken it down to Zermelo set theory. The following proof is my personal attempt to solve the question of whether we can have a version of replacement that can withstand removal of Extensionality when ZF is formalized with it instead of the standard axiom schema of replacement. Dana Scott had investigated that, the general lines of the proof here are similar to his; however, the form of Replacement suggested here is different.