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Mirrors > Home > ILE Home > Th. List > notnotnot | Unicode version |
Description: Triple negation. (Contributed by Jim Kingdon, 28-Jul-2018.) |
Ref | Expression |
---|---|
notnotnot |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | notnot 591 | . . 3 | |
2 | 1 | con3i 594 | . 2 |
3 | notnot 591 | . 2 | |
4 | 2, 3 | impbii 124 | 1 |
Colors of variables: wff set class |
Syntax hints: wn 3 wb 103 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia2 105 ax-ia3 106 ax-in1 576 ax-in2 577 |
This theorem depends on definitions: df-bi 115 |
This theorem is referenced by: stabnot 774 testbitestn 856 |
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