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Metamath Proof Explorer

Theorem olci

Description: Deduction introducing a disjunct. (Contributed by NM, 19-Jan-2008) (Proof shortened by Wolf Lammen, 14-Nov-2012)

		Ref	Expression
	Hypothesis	orci.1	$⊢ φ$
	Assertion	olci	$⊢ (ψ \lor φ)$

Step	Hyp	Ref	Expression
1		orci.1	$⊢ φ$
2	1	a1i	$⊢ \neg ψ \to φ$
3	2	orri	$⊢ (ψ \lor φ)$