Theorem orim1i

Description: Introduce disjunct to both sides of an implication. (Contributed by NM, 6-Jun-1994)

	Ref	Expression
Hypothesis	orim1i.1	$$⊢\phi \to \psi$$
Assertion	orim1i	$$⊢\left(\phi \vee \chi \right)\to \left(\psi \vee \chi \right)$$

Proof

Step	Hyp	Ref	Expression
1		orim1i.1	$$⊢\phi \to \psi$$
2		id	$$⊢\chi \to \chi$$
3	1 2	orim12i	$$⊢\left(\phi \vee \chi \right)\to \left(\psi \vee \chi \right)$$