Theorem pm3.42

Description: Theorem *3.42 of WhiteheadRussell p. 113. (Contributed by NM, 3-Jan-2005)

	Ref	Expression
Assertion	pm3.42	⊢ ( ( 𝜓 → 𝜒 ) → ( ( 𝜑 ∧ 𝜓 ) → 𝜒 ) )

Proof

Step	Hyp	Ref	Expression
1		simpr	⊢ ( ( 𝜑 ∧ 𝜓 ) → 𝜓 )
2	1	imim1i	⊢ ( ( 𝜓 → 𝜒 ) → ( ( 𝜑 ∧ 𝜓 ) → 𝜒 ) )