Metamath Proof Explorer


Theorem bnj1142

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

Ref Expression
Hypothesis bnj1142.1 φ x x A ψ
Assertion bnj1142 φ x A ψ

Proof

Step Hyp Ref Expression
1 bnj1142.1 φ x x A ψ
2 df-ral x A ψ x x A ψ
3 1 2 sylibr φ x A ψ