Theorem ax8v1

Description: First of two weakened versions of ax8v , with an extra disjoint variable condition on x , z , see comments there. (Contributed by BJ, 7-Dec-2020)

	Ref	Expression
Assertion	ax8v1	$$⊢x=y\to \left(x\in z\to y\in z\right)$$

Proof

Step	Hyp	Ref	Expression
1		ax8v	$$⊢x=y\to \left(x\in z\to y\in z\right)$$