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Mirrors > Home > ILE 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 | notnot 624 | . 2 ⊢ (𝜑 → ¬ ¬ 𝜑) | |
3 | 1, 2 | ax-mp 5 | 1 ⊢ ¬ ¬ 𝜑 |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-in1 609 ax-in2 610 |
This theorem is referenced by: nbn3 695 fal 1355 ax-9 1524 neirr 2349 dfnul2 3416 dfnul3 3417 rab0 3442 |
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