Theorem frege26 41418

Description: Identical to idd 24. Proposition 26 of [Frege1879] p. 42. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)

Assertion

Ref	Expression
frege26	⊢ (𝜑 → (𝜓 → 𝜓))

Proof of Theorem frege26

Step	Hyp	Ref	Expression
1		ax-frege1 41398	. 2 ⊢ (𝜓 → (𝜑 → 𝜓))
2		ax-frege8 41417	. 2 ⊢ ((𝜓 → (𝜑 → 𝜓)) → (𝜑 → (𝜓 → 𝜓)))
3	1, 2	ax-mp 5	1 ⊢ (𝜑 → (𝜓 → 𝜓))

Syntax hints:   → wi 4

This theorem was proved from axioms:  ax-mp 5  ax-frege1 41398  ax-frege8 41417

This theorem is referenced by:  frege27  41419