Metamath Proof Explorer


Theorem frege19

Description: A closed form of syl6 . Proposition 19 of Frege1879 p. 39. (Contributed by RP, 24-Dec-2019) (Proof modification is discouraged.)

Ref Expression
Assertion frege19 φ ψ χ χ θ φ ψ θ

Proof

Step Hyp Ref Expression
1 frege9 ψ χ χ θ ψ θ
2 frege18 ψ χ χ θ ψ θ φ ψ χ χ θ φ ψ θ
3 1 2 ax-mp φ ψ χ χ θ φ ψ θ