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Metamath Proof Explorer

Theorem pm2.43i

Description: Inference absorbing redundant antecedent. Inference associated with pm2.43 . (Contributed by NM, 10-Jan-1993) (Proof shortened by Mel L. O'Cat, 28-Nov-2008)

		Ref	Expression
	Hypothesis	pm2.43i.1	$⊢ φ \to (φ \to ψ)$
	Assertion	pm2.43i	$⊢ φ \to ψ$

Proof

Step	Hyp	Ref	Expression
1		pm2.43i.1	$⊢ φ \to (φ \to ψ)$
2		id	$⊢ φ \to φ$
3	2 1	mpd	$⊢ φ \to ψ$