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Theorem con3 134
Description: Contraposition. Theorem *2.16 of [WhiteheadRussell] p. 103. This was the fourth axiom of Frege, specifically Proposition 28 of [Frege1879] p. 43. (Contributed by NM, 29-Dec-1992.) (Proof shortened by Wolf Lammen, 13-Feb-2013.)
Assertion
Ref Expression
con3

Proof of Theorem con3
StepHypRef Expression
1 id 22 . 2
21con3d 133 1
Colors of variables: wff setvar class
Syntax hints:  -.wn 3  ->wi 4
This theorem is referenced by:  pm2.65  172  con34b  292  nic-ax  1506  nic-axALT  1507  eximOLD  1655  axc10  2004  ax12indn  2273  rexim  2922  ralf0  3936  dfon2lem9  29223  hbntg  29238  naim1  29850  naim2  29851  lukshef-ax2  29880  nrhmzr  32679  vk15.4j  33298  tratrb  33307  hbntal  33326  tratrbVD  33661  con5VD  33700  vk15.4jVD  33714  bj-axc10v  34277  cvrexchlem  35143  cvratlem  35145  axfrege28  37856
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
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