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Mirrors > Home > ILE Home > Th. List > notbi | Unicode version |
Description: Equivalence property for negation. Closed form. (Contributed by BJ, 27-Jan-2020.) |
Ref | Expression |
---|---|
notbi |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | biimpr 129 | . . 3 | |
2 | 1 | con3d 626 | . 2 |
3 | biimp 117 | . . 3 | |
4 | 3 | con3d 626 | . 2 |
5 | 2, 4 | impbid 128 | 1 |
Colors of variables: wff set class |
Syntax hints: wn 3 wi 4 wb 104 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-in1 609 ax-in2 610 |
This theorem depends on definitions: df-bi 116 |
This theorem is referenced by: notbid 662 notbii 663 ifbi 3546 |
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