Theorem pm2.43b 46

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

Hypothesis

Ref	Expression
pm2.43b.1	|- (ps -> (ph -> (ps -> ch)))

Assertion

Ref	Expression
pm2.43b	|- (ph -> (ps -> ch))

Proof of Theorem pm2.43b

Step	Hyp	Ref	Expression
1		pm2.43b.1	. . 3 |- (ps -> (ph -> (ps -> ch)))
2	1	pm2.43a 45	. 2 |- (ps -> (ph -> ch))
3	2	com12 27	1 |- (ph -> (ps -> ch))

This proof depends on syntax axioms:   -> wi 4

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7

This theorem is used by:  ncfinlower  4484  funfvima  5460