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| Mirrors > Home > MPE Home > Th. List > Mathboxes > conimpfalt | Structured version Visualization version GIF version | ||
| Description: Assuming a, not b, and a implies b, there exists a proof that a is false.) (Contributed by Jarvin Udandy, 29-Aug-2016.) | 
| Ref | Expression | 
|---|---|
| conimpfalt.1 | ⊢ 𝜑 | 
| conimpfalt.2 | ⊢ ¬ 𝜓 | 
| conimpfalt.3 | ⊢ (𝜑 → 𝜓) | 
| Ref | Expression | 
|---|---|
| conimpfalt | ⊢ (𝜑 ↔ ⊥) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | conimpfalt.3 | . 2 ⊢ (𝜑 → 𝜓) | |
| 2 | conimpfalt.2 | . 2 ⊢ ¬ 𝜓 | |
| 3 | 1, 2 | aibnbaif 46919 | 1 ⊢ (𝜑 ↔ ⊥) | 
| Colors of variables: wff setvar class | 
| Syntax hints: ¬ wn 3 → wi 4 ↔ wb 206 ⊥wfal 1552 | 
| 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 207 df-tru 1543 df-fal 1553 | 
| This theorem is referenced by: (None) | 
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