| Mathbox for Giovanni Mascellani |
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| Mirrors > Home > MPE Home > Th. List > Mathboxes > efald2 | Structured version Visualization version GIF version | ||
| Description: A proof by contradiction. (Contributed by Giovanni Mascellani, 15-Sep-2017.) |
| Ref | Expression |
|---|---|
| efald2.1 | ⊢ (¬ 𝜑 → ⊥) |
| Ref | Expression |
|---|---|
| efald2 | ⊢ 𝜑 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | efald2.1 | . . . 4 ⊢ (¬ 𝜑 → ⊥) | |
| 2 | 1 | adantl 481 | . . 3 ⊢ ((⊤ ∧ ¬ 𝜑) → ⊥) |
| 3 | 2 | efald 1561 | . 2 ⊢ (⊤ → 𝜑) |
| 4 | 3 | mptru 1547 | 1 ⊢ 𝜑 |
| Colors of variables: wff setvar class |
| Syntax hints: ¬ wn 3 → wi 4 ⊤wtru 1541 ⊥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-an 396 df-tru 1543 df-fal 1553 |
| This theorem is referenced by: mpobi123f 38169 mptbi12f 38173 ac6s6 38179 |
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