Metamath Proof Explorer


Theorem frege22

Description: A closed form of com45 . Proposition 22 of Frege1879 p. 41. (Contributed by RP, 24-Dec-2019) (Proof modification is discouraged.)

Ref Expression
Assertion frege22 φ ψ χ θ τ η φ ψ χ τ θ η

Proof

Step Hyp Ref Expression
1 frege16 ψ χ θ τ η ψ χ τ θ η
2 frege5 ψ χ θ τ η ψ χ τ θ η φ ψ χ θ τ η φ ψ χ τ θ η
3 1 2 ax-mp φ ψ χ θ τ η φ ψ χ τ θ η