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Mirrors > Home > NFE Home > Th. List > inegd | Unicode version |
Description: Negation introduction rule from natural deduction. (Contributed by Mario Carneiro, 9-Feb-2017.) |
Ref | Expression |
---|---|
inegd.1 |
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Ref | Expression |
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inegd |
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Step | Hyp | Ref | Expression |
---|---|---|---|
1 | inegd.1 |
. . 3
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2 | 1 | ex 423 |
. 2
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3 | dfnot 1332 |
. 2
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4 | 2, 3 | sylibr 203 |
1
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Colors of variables: wff setvar class |
Syntax hints: ![]() ![]() ![]() ![]() |
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 df-tru 1319 df-fal 1320 |
This theorem is referenced by: efald 1334 |
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