Theorem pm2.61-ocatOLD 125

Description: Theorem *2.61 of [WhiteheadRussell] p. 107. Useful for eliminating an antecedent. (The proof was shortened by O'Cat, 19-Feb-2008.)

Assertion

Ref	Expression
pm2.61-ocatOLD	|- ((ph -> ps) -> ((-. ph -> ps) -> ps))

Proof of Theorem pm2.61-ocatOLD

Step	Hyp	Ref	Expression
1		pm2.37OLD 99	. 2 |- ((ph -> ps) -> ((-. ph -> ps) -> (-. ps -> ps)))
2		pm2.18 81	. 2 |- ((-. ps -> ps) -> ps)
3	1, 2	syl6 22	1 |- ((ph -> ps) -> ((-. ph -> ps) -> ps))

Syntax hints:  -. wn 2   -> wi 3

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7

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