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Mirrors > Home > NFE Home > Th. List > notnoti | GIF version |
Description: Infer double negation. (Contributed by NM, 27-Feb-2008.) |
Ref | Expression |
---|---|
negbi.1 | ⊢ φ |
Ref | Expression |
---|---|
notnoti | ⊢ ¬ ¬ φ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | negbi.1 | . 2 ⊢ φ | |
2 | notnot1 114 | . 2 ⊢ (φ → ¬ ¬ φ) | |
3 | 1, 2 | ax-mp 5 | 1 ⊢ ¬ ¬ φ |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 |
This theorem is referenced by: nbn3 337 fal 1322 19.2OLD 1700 ax9dgen 1716 eqtfinrelk 4486 2p1e3c 6156 |
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