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| Mirrors > Home > MPE Home > Th. List > mopick | Structured version Visualization version GIF version | ||
| Description: "At most one" picks a variable value, eliminating an existential quantifier. (Contributed by NM, 27-Jan-1997.) (Proof shortened by Wolf Lammen, 17-Sep-2019.) |
| Ref | Expression |
|---|---|
| mopick | ⊢ ((∃*𝑥𝜑 ∧ ∃𝑥(𝜑 ∧ 𝜓)) → (𝜑 → 𝜓)) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | df-mo 2540 | . . 3 ⊢ (∃*𝑥𝜑 ↔ ∃𝑦∀𝑥(𝜑 → 𝑥 = 𝑦)) | |
| 2 | sp 2183 | . . . . 5 ⊢ (∀𝑥(𝜑 → 𝑥 = 𝑦) → (𝜑 → 𝑥 = 𝑦)) | |
| 3 | pm3.45 622 | . . . . . . 7 ⊢ ((𝜑 → 𝑥 = 𝑦) → ((𝜑 ∧ 𝜓) → (𝑥 = 𝑦 ∧ 𝜓))) | |
| 4 | 3 | aleximi 1832 | . . . . . 6 ⊢ (∀𝑥(𝜑 → 𝑥 = 𝑦) → (∃𝑥(𝜑 ∧ 𝜓) → ∃𝑥(𝑥 = 𝑦 ∧ 𝜓))) |
| 5 | ax12ev2 2180 | . . . . . 6 ⊢ (∃𝑥(𝑥 = 𝑦 ∧ 𝜓) → (𝑥 = 𝑦 → 𝜓)) | |
| 6 | 4, 5 | syl6 35 | . . . . 5 ⊢ (∀𝑥(𝜑 → 𝑥 = 𝑦) → (∃𝑥(𝜑 ∧ 𝜓) → (𝑥 = 𝑦 → 𝜓))) |
| 7 | 2, 6 | syl5d 73 | . . . 4 ⊢ (∀𝑥(𝜑 → 𝑥 = 𝑦) → (∃𝑥(𝜑 ∧ 𝜓) → (𝜑 → 𝜓))) |
| 8 | 7 | exlimiv 1930 | . . 3 ⊢ (∃𝑦∀𝑥(𝜑 → 𝑥 = 𝑦) → (∃𝑥(𝜑 ∧ 𝜓) → (𝜑 → 𝜓))) |
| 9 | 1, 8 | sylbi 217 | . 2 ⊢ (∃*𝑥𝜑 → (∃𝑥(𝜑 ∧ 𝜓) → (𝜑 → 𝜓))) |
| 10 | 9 | imp 406 | 1 ⊢ ((∃*𝑥𝜑 ∧ ∃𝑥(𝜑 ∧ 𝜓)) → (𝜑 → 𝜓)) |
| Colors of variables: wff setvar class |
| Syntax hints: → wi 4 ∧ wa 395 ∀wal 1538 ∃wex 1779 ∃*wmo 2538 |
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1795 ax-4 1809 ax-5 1910 ax-6 1967 ax-7 2007 ax-12 2177 |
| This theorem depends on definitions: df-bi 207 df-an 396 df-ex 1780 df-mo 2540 |
| This theorem is referenced by: moexexlem 2626 eupick 2633 mopick2 2637 morex 3725 imadif 6650 metsscmetcld 25349 |
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