Theorem issetiOLD

Description: Obsolete version of isseti as of 28-Aug-2023. A way to say " A is a set" (inference form). (Contributed by NM, 24-Jun-1993) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	isseti.1	⊢ 𝐴 ∈ V
Assertion	issetiOLD	⊢ ∃ 𝑥 𝑥 = 𝐴

Proof

Step	Hyp	Ref	Expression
1		isseti.1	⊢ 𝐴 ∈ V
2		isset	⊢ ( 𝐴 ∈ V ↔ ∃ 𝑥 𝑥 = 𝐴 )
3	1 2	mpbi	⊢ ∃ 𝑥 𝑥 = 𝐴