Metamath Proof Explorer


Theorem frege23

Description: Syllogism followed by rotation of three antecedents. Proposition 23 of Frege1879 p. 42. (Contributed by RP, 24-Dec-2019) (Proof modification is discouraged.)

Ref Expression
Assertion frege23 φ ψ χ θ τ φ ψ χ τ θ

Proof

Step Hyp Ref Expression
1 frege18 φ ψ χ θ τ φ ψ τ χ θ
2 frege22 φ ψ χ θ τ φ ψ τ χ θ φ ψ χ θ τ φ ψ χ τ θ
3 1 2 ax-mp φ ψ χ θ τ φ ψ χ τ θ