Metamath Proof Explorer


Theorem bnj1299

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

Ref Expression
Hypothesis bnj1299.1 φxAψχ
Assertion bnj1299 φxAψ

Proof

Step Hyp Ref Expression
1 bnj1299.1 φxAψχ
2 bnj1239 xAψχxAψ
3 1 2 syl φxAψ