3 ms·
No need to wonder for long, just have a look. Metamath: https://us.metamath.org/mpeuni/mmset.html#axioms https://us.metamath.org/mpeuni/mmset.html#axioms Isab
by robinzfc 2y ago
No need to wonder for long, just have a look.
Metamath: https://us.metamath.org/mpeuni/mmset.html#axioms https://us.metamath.org/mpeuni/mmset.html#axioms
Isabelle/ZF: https://isabelle.in.tum.de/dist/library/FOL/ZF/ZF_Base.html https://isabelle.in.tum.de/dist/library/FOL/ZF/ZF_Base.html