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Theorem con3th 949
 Description: Contraposition. Theorem *2.16 of [WhiteheadRussell] p. 103. This version of con3 134 demonstrates the use of the weak deduction theorem dedt 948 to derive it from con3i 135. (Contributed by NM, 27-Jun-2002.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
con3th

Proof of Theorem con3th
StepHypRef Expression
1 id 22 . . . 4
21notbid 294 . . 3
32imbi1d 317 . 2
41imbi2d 316 . . . 4
5 id 22 . . . . 5
65imbi2d 316 . . . 4
7 id 22 . . . 4
84, 6, 7elimh 947 . . 3
98con3i 135 . 2
103, 9dedt 948 1
 Colors of variables: wff setvar class Syntax hints:   wn 3   wi 4   wb 184   wo 368   wa 369 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  df-an 371 This theorem is referenced by: (None)
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