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Theorem pm2.01 162
Description: Reductio ad absurdum. Theorem *2.01 of [WhiteheadRussell] p. 100. (Contributed by NM, 18-Aug-1993.) (Proof shortened by O'Cat, 21-Nov-2008.) (Proof shortened by Wolf Lammen, 31-Oct-2012.)
Assertion
Ref Expression
pm2.01  |-  ( (
ph  ->  -.  ph )  ->  -.  ph )

Proof of Theorem pm2.01
StepHypRef Expression
1 id 21 . 2  |-  ( -. 
ph  ->  -.  ph )
21, 1ja 155 1  |-  ( (
ph  ->  -.  ph )  ->  -.  ph )
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6
This theorem is referenced by:  bijust  177  pm4.8  356  dtrucor2  4103  ominf  6960  elirr  7196  hfninf  23990
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10
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