Theorem pm2.01da

Description: Deduction based on reductio ad absurdum. See pm2.01 . (Contributed by Mario Carneiro, 9-Feb-2017)

	Ref	Expression
Hypothesis	pm2.01da.1	⊢ ( ( 𝜑 ∧ 𝜓 ) → ¬ 𝜓 )
Assertion	pm2.01da	⊢ ( 𝜑 → ¬ 𝜓 )

Proof

Step	Hyp	Ref	Expression
1		pm2.01da.1	⊢ ( ( 𝜑 ∧ 𝜓 ) → ¬ 𝜓 )
2	1	ex	⊢ ( 𝜑 → ( 𝜓 → ¬ 𝜓 ) )
3	2	pm2.01d	⊢ ( 𝜑 → ¬ 𝜓 )