Theorem bj-issettruALTV

Description: Moved to main as issettru and kept for the comments.

Weak version of isset without ax-ext . (Contributed by BJ, 24-Apr-2024) (Proof modification is discouraged.)

	Ref	Expression
Assertion	bj-issettruALTV	|- ( E. x x = A <-> A e. { y | T. } )

Proof

Step	Hyp	Ref	Expression
1		iseqsetv-clel	|- ( E. x x = A <-> E. z z = A )
2		issettru	|- ( E. z z = A <-> A e. { y | T. } )
3	1 2	bitri	|- ( E. x x = A <-> A e. { y | T. } )