Metamath Proof Explorer

Theorem pm3.44

Description: Theorem *3.44 of WhiteheadRussell p. 113. (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 3-Oct-2013)

		Ref	Expression
	Assertion	pm3.44	$⊢ ((ψ \to φ) \land (χ \to φ)) \to ((ψ \lor χ) \to φ)$

Step	Hyp	Ref	Expression
1		id	$⊢ (ψ \to φ) \to (ψ \to φ)$
2		id	$⊢ (χ \to φ) \to (χ \to φ)$
3	1 2	jaao	$⊢ ((ψ \to φ) \land (χ \to φ)) \to ((ψ \lor χ) \to φ)$