Metamath Proof Explorer


Theorem bnj946

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

Ref Expression
Hypothesis bnj946.1 φxAψ
Assertion bnj946 φxxAψ

Proof

Step Hyp Ref Expression
1 bnj946.1 φxAψ
2 df-ral xAψxxAψ
3 1 2 bitri φxxAψ