Theorem csb0OLD

Description: Obsolete version of csb0 as of 28-Jun-2024. (Contributed by NM, 18-Aug-2018) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	csb0OLD	⊢ ⦋ 𝐴 / 𝑥 ⦌ ∅ = ∅

Proof

Step	Hyp	Ref	Expression
1		csbconstg	⊢ ( 𝐴 ∈ V → ⦋ 𝐴 / 𝑥 ⦌ ∅ = ∅ )
2		csbprc	⊢ ( ¬ 𝐴 ∈ V → ⦋ 𝐴 / 𝑥 ⦌ ∅ = ∅ )
3	1 2	pm2.61i	⊢ ⦋ 𝐴 / 𝑥 ⦌ ∅ = ∅