Theorem jarl

Description: Elimination of a nested antecedent. (Contributed by Wolf Lammen, 10-May-2013)

	Ref	Expression
Assertion	jarl	⊢ ( ( ( 𝜑 → 𝜓 ) → 𝜒 ) → ( ¬ 𝜑 → 𝜒 ) )

Proof

Step	Hyp	Ref	Expression
1		pm2.21	⊢ ( ¬ 𝜑 → ( 𝜑 → 𝜓 ) )
2	1	imim1i	⊢ ( ( ( 𝜑 → 𝜓 ) → 𝜒 ) → ( ¬ 𝜑 → 𝜒 ) )