Theorem pm4.45

Description: Theorem *4.45 of WhiteheadRussell p. 119. (Contributed by NM, 3-Jan-2005)

	Ref	Expression
Assertion	pm4.45	$$⊢\phi \leftrightarrow \left(\phi \wedge \left(\phi \vee \psi \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		orc	$$⊢\phi \to \left(\phi \vee \psi \right)$$
2	1	pm4.71i	$$⊢\phi \leftrightarrow \left(\phi \wedge \left(\phi \vee \psi \right)\right)$$