Theorem ax9v1

Description: First of two weakened versions of ax9v , with an extra disjoint variable condition on x , z , see comments there. (Contributed by BJ, 7-Dec-2020)

	Ref	Expression
Assertion	ax9v1	⊢ ( 𝑥 = 𝑦 → ( 𝑧 ∈ 𝑥 → 𝑧 ∈ 𝑦 ) )

Proof

Step	Hyp	Ref	Expression
1		ax9v	⊢ ( 𝑥 = 𝑦 → ( 𝑧 ∈ 𝑥 → 𝑧 ∈ 𝑦 ) )