Theorem conax1

Description: Contrapositive of ax-1 . (Contributed by BJ, 28-Oct-2023)

	Ref	Expression
Assertion	conax1	⊢ ( ¬ ( 𝜑 → 𝜓 ) → ¬ 𝜓 )

Proof

Step	Hyp	Ref	Expression
1		ax-1	⊢ ( 𝜓 → ( 𝜑 → 𝜓 ) )
2	1	con3i	⊢ ( ¬ ( 𝜑 → 𝜓 ) → ¬ 𝜓 )