Description: Alternate proof of axnul , proved from propositional calculus,
ax-gen , ax-4 , ax-5 , and ax-inf2 . (Contributed by BTernaryTau, 22-Jun-2025)(Proof modification is discouraged.)(New usage is discouraged.)
|- ( ( E. x ( x e. z /\ A. y -. y e. x ) /\ A. x ( x e. z -> E. y ( y e. z /\ A. w ( w e. y <-> ( w e. x \/ w = x ) ) ) ) ) -> E. x ( x e. z /\ A. y -. y e. x ) )