Metamath Proof Explorer


Theorem bnj1247

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

Ref Expression
Hypothesis bnj1247.1 φ ψ χ θ τ
Assertion bnj1247 φ θ

Proof

Step Hyp Ref Expression
1 bnj1247.1 φ ψ χ θ τ
2 id θ θ
3 1 2 bnj771 φ θ