Theorem pm2.521g 176

Description: A general instance of Theorem *2.521 of [WhiteheadRussell] p. 107. (Contributed by BJ, 28-Oct-2023.)

Assertion

Ref	Expression
pm2.521g	⊢ (¬ (𝜑 → 𝜓) → (𝜓 → 𝜒))

Proof of Theorem pm2.521g

Step	Hyp	Ref	Expression
1		conax1 172	. 2 ⊢ (¬ (𝜑 → 𝜓) → ¬ 𝜓)
2	1	pm2.21d 121	1 ⊢ (¬ (𝜑 → 𝜓) → (𝜓 → 𝜒))

Syntax hints:  ¬ wn 3   → wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem is referenced by:  pm2.521  178  pm5.14  943