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Theorem pm2.65i 165
Description: Inference rule for proof by contradiction. (Contributed by NM, 18-May-1994.) (Proof shortened by Wolf Lammen, 11-Sep-2013.)
Hypotheses
Ref Expression
pm2.65i.1
pm2.65i.2
Assertion
Ref Expression
pm2.65i

Proof of Theorem pm2.65i
StepHypRef Expression
1 pm2.65i.2 . . 3
21con2i 112 . 2
3 pm2.65i.1 . . 3
43con3i 127 . 2
52, 4pm2.61i 156 1
Colors of variables: wff setvar class
Syntax hints:   wn 3   wi 4
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem is referenced by:  mto  167  mt2  170  noel  3554
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