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Mirrors > Home > MPE Home > Th. List > nbfal | Structured version Visualization version GIF version |
Description: The negation of a proposition is equivalent to itself being equivalent to ⊥. (Contributed by Anthony Hart, 14-Aug-2011.) |
Ref | Expression |
---|---|
nbfal | ⊢ (¬ 𝜑 ↔ (𝜑 ↔ ⊥)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | fal 1550 | . 2 ⊢ ¬ ⊥ | |
2 | 1 | nbn 375 | 1 ⊢ (¬ 𝜑 ↔ (𝜑 ↔ ⊥)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 208 ⊥wfal 1548 |
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 209 df-tru 1539 df-fal 1549 |
This theorem is referenced by: nulmo 2801 bisym1 33771 aisfina 43141 aifftbifffaibifff 43165 lindslinindsimp2 44525 |
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