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Theorem pm2.65da 559
Description: Deduction rule for proof by contradiction. (Contributed by NM, 12-Jun-2014.)
Hypotheses
Ref Expression
pm2.65da.1
pm2.65da.2
Assertion
Ref Expression
pm2.65da

Proof of Theorem pm2.65da
StepHypRef Expression
1 pm2.65da.1 . . 3
21ex 423 . 2
3 pm2.65da.2 . . 3
43ex 423 . 2
52, 4pm2.65d 166 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wi 4   wa 358
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 177  df-an 360
This theorem is referenced by:  condan  769
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