Metamath Proof Explorer


Theorem bnj1196

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

Ref Expression
Hypothesis bnj1196.1 φxAψ
Assertion bnj1196 φxxAψ

Proof

Step Hyp Ref Expression
1 bnj1196.1 φxAψ
2 df-rex xAψxxAψ
3 1 2 sylib φxxAψ