Metamath Proof Explorer


Theorem frege51

Description: Compare with jaod . Proposition 51 of Frege1879 p. 50. (Contributed by RP, 24-Dec-2019) (Proof modification is discouraged.)

Ref Expression
Assertion frege51 φ ψ χ θ χ φ ¬ ψ θ χ

Proof

Step Hyp Ref Expression
1 frege50 ψ χ θ χ ¬ ψ θ χ
2 frege18 ψ χ θ χ ¬ ψ θ χ φ ψ χ θ χ φ ¬ ψ θ χ
3 1 2 ax-mp φ ψ χ θ χ φ ¬ ψ θ χ