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Mirrors > Home > MPE Home > Th. List > eu4 | Structured version Visualization version GIF version |
Description: Uniqueness using implicit substitution. (Contributed by NM, 26-Jul-1995.) |
Ref | Expression |
---|---|
eu4.1 | ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) |
Ref | Expression |
---|---|
eu4 | ⊢ (∃!𝑥𝜑 ↔ (∃𝑥𝜑 ∧ ∀𝑥∀𝑦((𝜑 ∧ 𝜓) → 𝑥 = 𝑦))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-eu 2654 | . 2 ⊢ (∃!𝑥𝜑 ↔ (∃𝑥𝜑 ∧ ∃*𝑥𝜑)) | |
2 | eu4.1 | . . . 4 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) | |
3 | 2 | mo4 2650 | . . 3 ⊢ (∃*𝑥𝜑 ↔ ∀𝑥∀𝑦((𝜑 ∧ 𝜓) → 𝑥 = 𝑦)) |
4 | 3 | anbi2i 624 | . 2 ⊢ ((∃𝑥𝜑 ∧ ∃*𝑥𝜑) ↔ (∃𝑥𝜑 ∧ ∀𝑥∀𝑦((𝜑 ∧ 𝜓) → 𝑥 = 𝑦))) |
5 | 1, 4 | bitri 277 | 1 ⊢ (∃!𝑥𝜑 ↔ (∃𝑥𝜑 ∧ ∀𝑥∀𝑦((𝜑 ∧ 𝜓) → 𝑥 = 𝑦))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∀wal 1535 ∃wex 1780 ∃*wmo 2620 ∃!weu 2653 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 |
This theorem depends on definitions: df-bi 209 df-an 399 df-ex 1781 df-mo 2622 df-eu 2654 |
This theorem is referenced by: euind 3715 eqeuel 4322 uniintsn 4913 eusv1 5292 omeu 8211 eroveu 8392 climeu 14912 pceu 16183 initoeu2lem2 17275 psgneu 18634 gsumval3eu 19024 frgr3vlem2 28053 3vfriswmgrlem 28056 unirep 35003 rlimdmafv 43396 rlimdmafv2 43477 |
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