Theorem orcd

Description: Deduction introducing a disjunct. A translation of natural deduction rule \/ IR ( \/ insertion right), see natded . (Contributed by NM, 20-Sep-2007)

	Ref	Expression
Hypothesis	orcd.1	$$⊢\phi \to \psi$$
Assertion	orcd	$$⊢\phi \to \left(\psi \vee \chi \right)$$

Proof

Step	Hyp	Ref	Expression
1		orcd.1	$$⊢\phi \to \psi$$
2		orc	$$⊢\psi \to \left(\psi \vee \chi \right)$$
3	1 2	syl	$$⊢\phi \to \left(\psi \vee \chi \right)$$