Theorem pm2.521g

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

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

Proof

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