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Theorem frege25 38111
Description: Closed form for a1dd 50. Proposition 25 of [Frege1879] p. 42. (Contributed by RP, 24-Dec-2019.) (Proof modification is discouraged.)
Assertion
Ref Expression
frege25  |-  ( (
ph  ->  ( ps  ->  ch ) )  ->  ( ph  ->  ( ps  ->  ( th  ->  ch )
) ) )

Proof of Theorem frege25
StepHypRef Expression
1 frege24 38109 . 2  |-  ( ( ps  ->  ch )  ->  ( ps  ->  ( th  ->  ch ) ) )
2 frege5 38094 . 2  |-  ( ( ( ps  ->  ch )  ->  ( ps  ->  ( th  ->  ch )
) )  ->  (
( ph  ->  ( ps 
->  ch ) )  -> 
( ph  ->  ( ps 
->  ( th  ->  ch ) ) ) ) )
31, 2ax-mp 5 1  |-  ( (
ph  ->  ( ps  ->  ch ) )  ->  ( ph  ->  ( ps  ->  ( th  ->  ch )
) ) )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4
This theorem was proved from axioms:  ax-mp 5  ax-frege1 38084  ax-frege2 38085  ax-frege8 38103
This theorem is referenced by:  frege111  38268
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