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Theorem pm2.61 165
Description: Theorem *2.61 of [WhiteheadRussell] p. 107. Useful for eliminating an antecedent. (Contributed by NM, 5-Aug-1993.) (Proof shortened by Wolf Lammen, 22-Sep-2013.)
Assertion
Ref Expression
pm2.61  |-  ( (
ph  ->  ps )  -> 
( ( -.  ph  ->  ps )  ->  ps ) )

Proof of Theorem pm2.61
StepHypRef Expression
1 pm2.6 164 . 2  |-  ( ( -.  ph  ->  ps )  ->  ( ( ph  ->  ps )  ->  ps )
)
21com12 29 1  |-  ( (
ph  ->  ps )  -> 
( ( -.  ph  ->  ps )  ->  ps ) )
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6
This theorem is referenced by:  onfrALT  27585  onfrALTVD  27935  bnj1109  28085  isltrn2N  29576  ltrnid  29591  ltrneq  29605
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10
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