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 φxxAψ
Assertion bnj1142 φxAψ

Proof

Step Hyp Ref Expression
1 bnj1142.1 φxxAψ
2 df-ral xAψxxAψ
3 1 2 sylibr φxAψ