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Metamath Proof Explorer

Theorem pm2.46

Description: Theorem *2.46 of WhiteheadRussell p. 106. (Contributed by NM, 3-Jan-2005)

		Ref	Expression
	Assertion	pm2.46	$⊢ \neg (φ \lor ψ) \to \neg ψ$

Step	Hyp	Ref	Expression
1		olc	$⊢ ψ \to (φ \lor ψ)$
2	1	con3i	$⊢ \neg (φ \lor ψ) \to \neg ψ$