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Mirrors > Home > MPE Home > Th. List > nbbn | Structured version Visualization version Unicode version |
Description: Move negation outside of biconditional. Compare Theorem *5.18 of [WhiteheadRussell] p. 124. (Contributed by NM, 27-Jun-2002.) (Proof shortened by Wolf Lammen, 20-Sep-2013.) |
Ref | Expression |
---|---|
nbbn |
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Step | Hyp | Ref | Expression |
---|---|---|---|
1 | xor3 359 |
. 2
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2 | con2bi 330 |
. 2
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3 | bicom 204 |
. 2
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4 | 1, 2, 3 | 3bitrri 276 |
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 189 |
This theorem is referenced by: biass 361 pclem6 941 xorass 1409 xorassOLD 1410 xorneg1OLD 1418 trubifalOLD 1483 hadbi 1501 canth 6249 qextltlem 11495 onint1 31109 notbinot1 32312 notbinot2 32316 |
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