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Metamath Proof Explorer

Theorem nfab1

Description: Bound-variable hypothesis builder for a class abstraction. (Contributed by Mario Carneiro, 11-Aug-2016)

Ref Expression
Assertion nfab1 Ⅎ 𝑥 { 𝑥 ∣ 𝜑 }

Proof

Step Hyp Ref Expression
1 nfsab1 ⊢ Ⅎ 𝑥 𝑦 ∈ { 𝑥 ∣ 𝜑 }
2 1 nfci ⊢ Ⅎ 𝑥 { 𝑥 ∣ 𝜑 }