Metamath Proof Explorer


Theorem bnj1219

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

Ref Expression
Hypotheses bnj1219.1 χ φ ψ ζ
bnj1219.2 θ χ τ η
Assertion bnj1219 θ ψ

Proof

Step Hyp Ref Expression
1 bnj1219.1 χ φ ψ ζ
2 bnj1219.2 θ χ τ η
3 1 simp2bi χ ψ
4 2 3 bnj835 θ ψ