Theorem pm5.36

Description: Theorem *5.36 of WhiteheadRussell p. 125. (Contributed by NM, 3-Jan-2005)

	Ref	Expression
Assertion	pm5.36	$$⊢\left(\phi \wedge \left(\phi \leftrightarrow \psi \right)\right)\leftrightarrow \left(\psi \wedge \left(\phi \leftrightarrow \psi \right)\right)$$

Proof

Step	Hyp	Ref	Expression
1		id	$$⊢\left(\phi \leftrightarrow \psi \right)\to \left(\phi \leftrightarrow \psi \right)$$
2	1	pm5.32ri	$$⊢\left(\phi \wedge \left(\phi \leftrightarrow \psi \right)\right)\leftrightarrow \left(\psi \wedge \left(\phi \leftrightarrow \psi \right)\right)$$