Theorem pm2.43b

Description: Inference absorbing redundant antecedent. (Contributed by NM, 31-Oct-1995)

	Ref	Expression
Hypothesis	pm2.43b.1	$$⊢\psi \to \left(\phi \to \left(\psi \to \chi \right)\right)$$
Assertion	pm2.43b	$$⊢\phi \to \left(\psi \to \chi \right)$$

Proof

Step	Hyp	Ref	Expression
1		pm2.43b.1	$$⊢\psi \to \left(\phi \to \left(\psi \to \chi \right)\right)$$
2	1	pm2.43a	$$⊢\psi \to \left(\phi \to \chi \right)$$
3	2	com12	$$⊢\phi \to \left(\psi \to \chi \right)$$