Theorem orbi1r

Description: orbi1 with order of disjuncts reversed. Derived from orbi1rVD . (Contributed by Alan Sare, 31-Dec-2011) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	orbi1r	$$⊢\left(\phi \leftrightarrow \psi \right)\to \left(\left(\chi \vee \phi \right)\leftrightarrow \left(\chi \vee \psi \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		id	$$⊢\left(\phi \leftrightarrow \psi \right)\to \left(\phi \leftrightarrow \psi \right)$$
2	1	orbi2d	$$⊢\left(\phi \leftrightarrow \psi \right)\to \left(\left(\chi \vee \phi \right)\leftrightarrow \left(\chi \vee \psi \right)\right)$$