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Metamath Proof Explorer

Theorem orim2

Description: Axiom *1.6 (Sum) of WhiteheadRussell p. 97. (Contributed by NM, 3-Jan-2005)

		Ref	Expression
	Assertion	orim2	$⊢ (ψ \to χ) \to ((φ \lor ψ) \to (φ \lor χ))$

Step	Hyp	Ref	Expression
1		id	$⊢ (ψ \to χ) \to (ψ \to χ)$
2	1	orim2d	$⊢ (ψ \to χ) \to ((φ \lor ψ) \to (φ \lor χ))$