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Theorem rb-ax3 1574
Description: The third of four axioms in the Russell-Bernays axiom system. (Contributed by Anthony Hart, 13-Aug-2011.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
rb-ax3  |-  ( -. 
ph  \/  ( ps  \/  ph ) )

Proof of Theorem rb-ax3
StepHypRef Expression
1 pm2.46 398 . . 3  |-  ( -.  ( ps  \/  ph )  ->  -.  ph )
21con1i 129 . 2  |-  ( -. 
-.  ph  ->  ( ps  \/  ph ) )
32orri 376 1  |-  ( -. 
ph  \/  ( ps  \/  ph ) )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    \/ wo 368
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 185  df-or 370
This theorem is referenced by:  rblem2  1578  rblem4  1580  rblem5  1581  rblem6  1582  rblem7  1583  re2luk1  1585  re2luk2  1586  re2luk3  1587
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