Theorem pm2.62

Description: Theorem *2.62 of WhiteheadRussell p. 107. (Contributed by NM, 3-Jan-2005) (Proof shortened by Wolf Lammen, 13-Dec-2013)

	Ref	Expression
Assertion	pm2.62	$$⊢\left(\phi \vee \psi \right)\to \left(\left(\phi \to \psi \right)\to \psi \right)$$

Proof

Step	Hyp	Ref	Expression
1		pm2.621	$$⊢\left(\phi \to \psi \right)\to \left(\left(\phi \vee \psi \right)\to \psi \right)$$
2	1	com12	$$⊢\left(\phi \vee \psi \right)\to \left(\left(\phi \to \psi \right)\to \psi \right)$$