HomeTheorem List (p. 246 of 480)
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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | retopon 24501 | The standard topology on the reals is a topology on the reals. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ (topGen‘ran (,)) ∈ (TopOn‘ℝ) | ||
| Theorem | retps 24502 | The standard topological space on the reals. (Contributed by NM, 19-Oct-2012.) |
| ⊢ 𝐾 = {⟨(Base‘ndx), ℝ⟩, ⟨(TopSet‘ndx), (topGen‘ran (,))⟩} ⇒ ⊢ 𝐾 ∈ TopSp | ||
| Theorem | iooretop 24503 | Open intervals are open sets of the standard topology on the reals . (Contributed by FL, 18-Jun-2007.) |
| ⊢ (𝐴(,)𝐵) ∈ (topGen‘ran (,)) | ||
| Theorem | icccld 24504 | Closed intervals are closed sets of the standard topology on ℝ. (Contributed by FL, 14-Sep-2007.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴[,]𝐵) ∈ (Clsd‘(topGen‘ran (,)))) | ||
| Theorem | icopnfcld 24505 | Right-unbounded closed intervals are closed sets of the standard topology on ℝ. (Contributed by Mario Carneiro, 17-Feb-2015.) |
| ⊢ (𝐴 ∈ ℝ → (𝐴[,)+∞) ∈ (Clsd‘(topGen‘ran (,)))) | ||
| Theorem | iocmnfcld 24506 | Left-unbounded closed intervals are closed sets of the standard topology on ℝ. (Contributed by Mario Carneiro, 17-Feb-2015.) |
| ⊢ (𝐴 ∈ ℝ → (-∞(,]𝐴) ∈ (Clsd‘(topGen‘ran (,)))) | ||
| Theorem | qdensere 24507 | ℚ is dense in the standard topology on ℝ. (Contributed by NM, 1-Mar-2007.) |
| ⊢ ((cls‘(topGen‘ran (,)))‘ℚ) = ℝ | ||
| Theorem | cnmetdval 24508 | Value of the distance function of the metric space of complex numbers. (Contributed by NM, 9-Dec-2006.) (Revised by Mario Carneiro, 27-Dec-2014.) |
| ⊢ 𝐷 = (abs ∘ − ) ⇒ ⊢ ((𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ) → (𝐴𝐷𝐵) = (abs‘(𝐴 − 𝐵))) | ||
| Theorem | cnmet 24509 | The absolute value metric determines a metric space on the complex numbers. This theorem provides a link between complex numbers and metrics spaces, making metric space theorems available for use with complex numbers. (Contributed by FL, 9-Oct-2006.) |
| ⊢ (abs ∘ − ) ∈ (Met‘ℂ) | ||
| Theorem | cnxmet 24510 | The absolute value metric is an extended metric. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ (abs ∘ − ) ∈ (∞Met‘ℂ) | ||
| Theorem | cnbl0 24511 | Two ways to write the open ball centered at zero. (Contributed by Mario Carneiro, 8-Sep-2015.) |
| ⊢ 𝐷 = (abs ∘ − ) ⇒ ⊢ (𝑅 ∈ ℝ* → (◡abs “ (0[,)𝑅)) = (0(ball‘𝐷)𝑅)) | ||
| Theorem | cnblcld 24512* | Two ways to write the closed ball centered at zero. (Contributed by Mario Carneiro, 8-Sep-2015.) |
| ⊢ 𝐷 = (abs ∘ − ) ⇒ ⊢ (𝑅 ∈ ℝ* → (◡abs “ (0[,]𝑅)) = {𝑥 ∈ ℂ ∣ (0𝐷𝑥) ≤ 𝑅}) | ||
| Theorem | cnfldms 24513 | The complex number field is a metric space. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ ℂfld ∈ MetSp | ||
| Theorem | cnfldxms 24514 | The complex number field is a topological space. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ ℂfld ∈ ∞MetSp | ||
| Theorem | cnfldtps 24515 | The complex number field is a topological space. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ ℂfld ∈ TopSp | ||
| Theorem | cnfldnm 24516 | The norm of the field of complex numbers. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ abs = (norm‘ℂfld) | ||
| Theorem | cnngp 24517 | The complex numbers form a normed group. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ ℂfld ∈ NrmGrp | ||
| Theorem | cnnrg 24518 | The complex numbers form a normed ring. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ ℂfld ∈ NrmRing | ||
| Theorem | cnfldtopn 24519 | The topology of the complex numbers. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 = (MetOpen‘(abs ∘ − )) | ||
| Theorem | cnfldtopon 24520 | The topology of the complex numbers is a topology. (Contributed by Mario Carneiro, 2-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ (TopOn‘ℂ) | ||
| Theorem | cnfldtop 24521 | The topology of the complex numbers is a topology. (Contributed by Mario Carneiro, 2-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ Top | ||
| Theorem | cnfldhaus 24522 | The topology of the complex numbers is Hausdorff. (Contributed by Mario Carneiro, 8-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ Haus | ||
| Theorem | unicntop 24523 | The underlying set of the standard topology on the complex numbers is the set of complex numbers. (Contributed by Glauco Siliprandi, 11-Dec-2019.) |
| ⊢ ℂ = ∪ (TopOpen‘ℂfld) | ||
| Theorem | cnopn 24524 | The set of complex numbers is open with respect to the standard topology on complex numbers. (Contributed by Glauco Siliprandi, 11-Dec-2019.) |
| ⊢ ℂ ∈ (TopOpen‘ℂfld) | ||
| Theorem | zringnrg 24525 | The ring of integers is a normed ring. (Contributed by AV, 13-Jun-2019.) |
| ⊢ ℤring ∈ NrmRing | ||
| Theorem | remetdval 24526 | Value of the distance function of the metric space of real numbers. (Contributed by NM, 16-May-2007.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴𝐷𝐵) = (abs‘(𝐴 − 𝐵))) | ||
| Theorem | remet 24527 | The absolute value metric determines a metric space on the reals. (Contributed by NM, 10-Feb-2007.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ 𝐷 ∈ (Met‘ℝ) | ||
| Theorem | rexmet 24528 | The absolute value metric is an extended metric. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ 𝐷 ∈ (∞Met‘ℝ) | ||
| Theorem | bl2ioo 24529 | A ball in terms of an open interval of reals. (Contributed by NM, 18-May-2007.) (Revised by Mario Carneiro, 13-Nov-2013.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴(ball‘𝐷)𝐵) = ((𝐴 − 𝐵)(,)(𝐴 + 𝐵))) | ||
| Theorem | ioo2bl 24530 | An open interval of reals in terms of a ball. (Contributed by NM, 18-May-2007.) (Revised by Mario Carneiro, 28-Aug-2015.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴(,)𝐵) = (((𝐴 + 𝐵) / 2)(ball‘𝐷)((𝐵 − 𝐴) / 2))) | ||
| Theorem | ioo2blex 24531 | An open interval of reals in terms of a ball. (Contributed by Mario Carneiro, 14-Nov-2013.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → (𝐴(,)𝐵) ∈ ran (ball‘𝐷)) | ||
| Theorem | blssioo 24532 | The balls of the standard real metric space are included in the open real intervals. (Contributed by NM, 8-May-2007.) (Revised by Mario Carneiro, 13-Nov-2013.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ ran (ball‘𝐷) ⊆ ran (,) | ||
| Theorem | tgioo 24533 | The topology generated by open intervals of reals is the same as the open sets of the standard metric space on the reals. (Contributed by NM, 7-May-2007.) (Revised by Mario Carneiro, 13-Nov-2013.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) & ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ (topGen‘ran (,)) = 𝐽 | ||
| Theorem | qdensere2 24534 | ℚ is dense in ℝ. (Contributed by NM, 24-Aug-2007.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) & ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ ((cls‘𝐽)‘ℚ) = ℝ | ||
| Theorem | blcvx 24535 | An open ball in the complex numbers is a convex set. (Contributed by Mario Carneiro, 12-Feb-2015.) (Revised by Mario Carneiro, 8-Sep-2015.) |
| ⊢ 𝑆 = (𝑃(ball‘(abs ∘ − ))𝑅) ⇒ ⊢ (((𝑃 ∈ ℂ ∧ 𝑅 ∈ ℝ*) ∧ (𝐴 ∈ 𝑆 ∧ 𝐵 ∈ 𝑆 ∧ 𝑇 ∈ (0[,]1))) → ((𝑇 · 𝐴) + ((1 − 𝑇) · 𝐵)) ∈ 𝑆) | ||
| Theorem | rehaus 24536 | The standard topology on the reals is Hausdorff. (Contributed by NM, 8-Mar-2007.) |
| ⊢ (topGen‘ran (,)) ∈ Haus | ||
| Theorem | tgqioo 24537 | The topology generated by open intervals of reals with rational endpoints is the same as the open sets of the standard metric space on the reals. In particular, this proves that the standard topology on the reals is second-countable. (Contributed by Mario Carneiro, 17-Jun-2014.) |
| ⊢ 𝑄 = (topGen‘((,) “ (ℚ × ℚ))) ⇒ ⊢ (topGen‘ran (,)) = 𝑄 | ||
| Theorem | re2ndc 24538 | The standard topology on the reals is second-countable. (Contributed by Mario Carneiro, 21-Mar-2015.) |
| ⊢ (topGen‘ran (,)) ∈ 2ndω | ||
| Theorem | resubmet 24539 | The subspace topology induced by a subset of the reals. (Contributed by Jeff Madsen, 2-Sep-2009.) (Revised by Mario Carneiro, 13-Aug-2014.) |
| ⊢ 𝑅 = (topGen‘ran (,)) & ⊢ 𝐽 = (MetOpen‘((abs ∘ − ) ↾ (𝐴 × 𝐴))) ⇒ ⊢ (𝐴 ⊆ ℝ → 𝐽 = (𝑅 ↾t 𝐴)) | ||
| Theorem | tgioo2 24540 | The standard topology on the reals is a subspace of the complex metric topology. (Contributed by Mario Carneiro, 13-Aug-2014.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ (topGen‘ran (,)) = (𝐽 ↾t ℝ) | ||
| Theorem | rerest 24541 | The subspace topology induced by a subset of the reals. (Contributed by Mario Carneiro, 13-Aug-2014.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) & ⊢ 𝑅 = (topGen‘ran (,)) ⇒ ⊢ (𝐴 ⊆ ℝ → (𝐽 ↾t 𝐴) = (𝑅 ↾t 𝐴)) | ||
| Theorem | tgioo3 24542 | The standard topology on the reals is a subspace of the complex metric topology. (Contributed by Mario Carneiro, 13-Aug-2014.) (Revised by Thierry Arnoux, 3-Jul-2019.) |
| ⊢ 𝐽 = (TopOpen‘ℝfld) ⇒ ⊢ (topGen‘ran (,)) = 𝐽 | ||
| Theorem | xrtgioo 24543 | The topology on the extended reals coincides with the standard topology on the reals, when restricted to ℝ. (Contributed by Mario Carneiro, 3-Sep-2015.) |
| ⊢ 𝐽 = ((ordTop‘ ≤ ) ↾t ℝ) ⇒ ⊢ (topGen‘ran (,)) = 𝐽 | ||
| Theorem | xrrest 24544 | The subspace topology induced by a subset of the reals. (Contributed by Mario Carneiro, 9-Sep-2015.) |
| ⊢ 𝑋 = (ordTop‘ ≤ ) & ⊢ 𝑅 = (topGen‘ran (,)) ⇒ ⊢ (𝐴 ⊆ ℝ → (𝑋 ↾t 𝐴) = (𝑅 ↾t 𝐴)) | ||
| Theorem | xrrest2 24545 | The subspace topology induced by a subset of the reals. (Contributed by Mario Carneiro, 9-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) & ⊢ 𝑋 = (ordTop‘ ≤ ) ⇒ ⊢ (𝐴 ⊆ ℝ → (𝐽 ↾t 𝐴) = (𝑋 ↾t 𝐴)) | ||
| Theorem | xrsxmet 24546 | The metric on the extended reals is a proper extended metric. (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐷 = (dist‘ℝ*𝑠) ⇒ ⊢ 𝐷 ∈ (∞Met‘ℝ*) | ||
| Theorem | xrsdsre 24547 | The metric on the extended reals coincides with the usual metric on the reals. (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐷 = (dist‘ℝ*𝑠) ⇒ ⊢ (𝐷 ↾ (ℝ × ℝ)) = ((abs ∘ − ) ↾ (ℝ × ℝ)) | ||
| Theorem | xrsblre 24548 | Any ball of the metric of the extended reals centered on an element of ℝ is entirely contained in ℝ. (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐷 = (dist‘ℝ*𝑠) ⇒ ⊢ ((𝑃 ∈ ℝ ∧ 𝑅 ∈ ℝ*) → (𝑃(ball‘𝐷)𝑅) ⊆ ℝ) | ||
| Theorem | xrsmopn 24549 | The metric on the extended reals generates a topology, but this does not match the order topology on ℝ*; for example {+∞} is open in the metric topology, but not the order topology. However, the metric topology is finer than the order topology, meaning that all open intervals are open in the metric topology. (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐷 = (dist‘ℝ*𝑠) & ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ (ordTop‘ ≤ ) ⊆ 𝐽 | ||
| Theorem | zcld 24550 | The integers are a closed set in the topology on ℝ. (Contributed by Mario Carneiro, 17-Feb-2015.) |
| ⊢ 𝐽 = (topGen‘ran (,)) ⇒ ⊢ ℤ ∈ (Clsd‘𝐽) | ||
| Theorem | recld2 24551 | The real numbers are a closed set in the topology on ℂ. (Contributed by Mario Carneiro, 17-Feb-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ ℝ ∈ (Clsd‘𝐽) | ||
| Theorem | zcld2 24552 | The integers are a closed set in the topology on ℂ. (Contributed by Mario Carneiro, 17-Feb-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ ℤ ∈ (Clsd‘𝐽) | ||
| Theorem | zdis 24553 | The integers are a discrete set in the topology on ℂ. (Contributed by Mario Carneiro, 19-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ (𝐽 ↾t ℤ) = 𝒫 ℤ | ||
| Theorem | sszcld 24554 | Every subset of the integers are closed in the topology on ℂ. (Contributed by Mario Carneiro, 6-Jul-2017.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ (𝐴 ⊆ ℤ → 𝐴 ∈ (Clsd‘𝐽)) | ||
| Theorem | reperflem 24555* | A subset of the real numbers that is closed under addition with real numbers is perfect. (Contributed by Mario Carneiro, 26-Dec-2016.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) & ⊢ ((𝑢 ∈ 𝑆 ∧ 𝑣 ∈ ℝ) → (𝑢 + 𝑣) ∈ 𝑆) & ⊢ 𝑆 ⊆ ℂ ⇒ ⊢ (𝐽 ↾t 𝑆) ∈ Perf | ||
| Theorem | reperf 24556 | The real numbers are a perfect subset of the complex numbers. (Contributed by Mario Carneiro, 26-Dec-2016.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ (𝐽 ↾t ℝ) ∈ Perf | ||
| Theorem | cnperf 24557 | The complex numbers are a perfect space. (Contributed by Mario Carneiro, 26-Dec-2016.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ Perf | ||
| Theorem | iccntr 24558 | The interior of a closed interval in the standard topology on ℝ is the corresponding open interval. (Contributed by Mario Carneiro, 1-Sep-2014.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((int‘(topGen‘ran (,)))‘(𝐴[,]𝐵)) = (𝐴(,)𝐵)) | ||
| Theorem | icccmplem1 24559* | Lemma for icccmp 24562. (Contributed by Mario Carneiro, 18-Jun-2014.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝑇 = (𝐽 ↾t (𝐴[,]𝐵)) & ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) & ⊢ 𝑆 = {𝑥 ∈ (𝐴[,]𝐵) ∣ ∃𝑧 ∈ (𝒫 𝑈 ∩ Fin)(𝐴[,]𝑥) ⊆ ∪ 𝑧} & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → 𝐴 ≤ 𝐵) & ⊢ (𝜑 → 𝑈 ⊆ 𝐽) & ⊢ (𝜑 → (𝐴[,]𝐵) ⊆ ∪ 𝑈) ⇒ ⊢ (𝜑 → (𝐴 ∈ 𝑆 ∧ ∀𝑦 ∈ 𝑆 𝑦 ≤ 𝐵)) | ||
| Theorem | icccmplem2 24560* | Lemma for icccmp 24562. (Contributed by Mario Carneiro, 13-Jun-2014.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝑇 = (𝐽 ↾t (𝐴[,]𝐵)) & ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) & ⊢ 𝑆 = {𝑥 ∈ (𝐴[,]𝐵) ∣ ∃𝑧 ∈ (𝒫 𝑈 ∩ Fin)(𝐴[,]𝑥) ⊆ ∪ 𝑧} & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → 𝐴 ≤ 𝐵) & ⊢ (𝜑 → 𝑈 ⊆ 𝐽) & ⊢ (𝜑 → (𝐴[,]𝐵) ⊆ ∪ 𝑈) & ⊢ (𝜑 → 𝑉 ∈ 𝑈) & ⊢ (𝜑 → 𝐶 ∈ ℝ+) & ⊢ (𝜑 → (𝐺(ball‘𝐷)𝐶) ⊆ 𝑉) & ⊢ 𝐺 = sup(𝑆, ℝ, < ) & ⊢ 𝑅 = if((𝐺 + (𝐶 / 2)) ≤ 𝐵, (𝐺 + (𝐶 / 2)), 𝐵) ⇒ ⊢ (𝜑 → 𝐵 ∈ 𝑆) | ||
| Theorem | icccmplem3 24561* | Lemma for icccmp 24562. (Contributed by Mario Carneiro, 13-Jun-2014.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝑇 = (𝐽 ↾t (𝐴[,]𝐵)) & ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) & ⊢ 𝑆 = {𝑥 ∈ (𝐴[,]𝐵) ∣ ∃𝑧 ∈ (𝒫 𝑈 ∩ Fin)(𝐴[,]𝑥) ⊆ ∪ 𝑧} & ⊢ (𝜑 → 𝐴 ∈ ℝ) & ⊢ (𝜑 → 𝐵 ∈ ℝ) & ⊢ (𝜑 → 𝐴 ≤ 𝐵) & ⊢ (𝜑 → 𝑈 ⊆ 𝐽) & ⊢ (𝜑 → (𝐴[,]𝐵) ⊆ ∪ 𝑈) ⇒ ⊢ (𝜑 → 𝐵 ∈ 𝑆) | ||
| Theorem | icccmp 24562 | A closed interval in ℝ is compact. (Contributed by Mario Carneiro, 13-Jun-2014.) |
| ⊢ 𝐽 = (topGen‘ran (,)) & ⊢ 𝑇 = (𝐽 ↾t (𝐴[,]𝐵)) ⇒ ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → 𝑇 ∈ Comp) | ||
| Theorem | reconnlem1 24563 | Lemma for reconn 24565. Connectedness in the reals-easy direction. (Contributed by Jeff Hankins, 13-Jul-2009.) (Proof shortened by Mario Carneiro, 9-Sep-2015.) |
| ⊢ (((𝐴 ⊆ ℝ ∧ ((topGen‘ran (,)) ↾t 𝐴) ∈ Conn) ∧ (𝑋 ∈ 𝐴 ∧ 𝑌 ∈ 𝐴)) → (𝑋[,]𝑌) ⊆ 𝐴) | ||
| Theorem | reconnlem2 24564* | Lemma for reconn 24565. (Contributed by Jeff Hankins, 17-Aug-2009.) (Proof shortened by Mario Carneiro, 9-Sep-2015.) |
| ⊢ (𝜑 → 𝐴 ⊆ ℝ) & ⊢ (𝜑 → 𝑈 ∈ (topGen‘ran (,))) & ⊢ (𝜑 → 𝑉 ∈ (topGen‘ran (,))) & ⊢ (𝜑 → ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥[,]𝑦) ⊆ 𝐴) & ⊢ (𝜑 → 𝐵 ∈ (𝑈 ∩ 𝐴)) & ⊢ (𝜑 → 𝐶 ∈ (𝑉 ∩ 𝐴)) & ⊢ (𝜑 → (𝑈 ∩ 𝑉) ⊆ (ℝ ∖ 𝐴)) & ⊢ (𝜑 → 𝐵 ≤ 𝐶) & ⊢ 𝑆 = sup((𝑈 ∩ (𝐵[,]𝐶)), ℝ, < ) ⇒ ⊢ (𝜑 → ¬ 𝐴 ⊆ (𝑈 ∪ 𝑉)) | ||
| Theorem | reconn 24565* | A subset of the reals is connected iff it has the interval property. (Contributed by Jeff Hankins, 15-Jul-2009.) (Proof shortened by Mario Carneiro, 9-Sep-2015.) |
| ⊢ (𝐴 ⊆ ℝ → (((topGen‘ran (,)) ↾t 𝐴) ∈ Conn ↔ ∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐴 (𝑥[,]𝑦) ⊆ 𝐴)) | ||
| Theorem | retopconn 24566 | Corollary of reconn 24565. The set of real numbers is connected. (Contributed by Jeff Hankins, 17-Aug-2009.) |
| ⊢ (topGen‘ran (,)) ∈ Conn | ||
| Theorem | iccconn 24567 | A closed interval is connected. (Contributed by Jeff Hankins, 17-Aug-2009.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((topGen‘ran (,)) ↾t (𝐴[,]𝐵)) ∈ Conn) | ||
| Theorem | opnreen 24568 | Every nonempty open set is uncountable. (Contributed by Mario Carneiro, 26-Jul-2014.) (Revised by Mario Carneiro, 20-Feb-2015.) |
| ⊢ ((𝐴 ∈ (topGen‘ran (,)) ∧ 𝐴 ≠ ∅) → 𝐴 ≈ 𝒫 ℕ) | ||
| Theorem | rectbntr0 24569 | A countable subset of the reals has empty interior. (Contributed by Mario Carneiro, 26-Jul-2014.) |
| ⊢ ((𝐴 ⊆ ℝ ∧ 𝐴 ≼ ℕ) → ((int‘(topGen‘ran (,)))‘𝐴) = ∅) | ||
| Theorem | xrge0gsumle 24570 | A finite sum in the nonnegative extended reals is monotonic in the support. (Contributed by Mario Carneiro, 13-Sep-2015.) |
| ⊢ 𝐺 = (ℝ*𝑠 ↾s (0[,]+∞)) & ⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ (𝜑 → 𝐹:𝐴⟶(0[,]+∞)) & ⊢ (𝜑 → 𝐵 ∈ (𝒫 𝐴 ∩ Fin)) & ⊢ (𝜑 → 𝐶 ⊆ 𝐵) ⇒ ⊢ (𝜑 → (𝐺 Σg (𝐹 ↾ 𝐶)) ≤ (𝐺 Σg (𝐹 ↾ 𝐵))) | ||
| Theorem | xrge0tsms 24571* | Any finite or infinite sum in the nonnegative extended reals is uniquely convergent to the supremum of all finite sums. (Contributed by Mario Carneiro, 13-Sep-2015.) (Proof shortened by AV, 26-Jul-2019.) |
| ⊢ 𝐺 = (ℝ*𝑠 ↾s (0[,]+∞)) & ⊢ (𝜑 → 𝐴 ∈ 𝑉) & ⊢ (𝜑 → 𝐹:𝐴⟶(0[,]+∞)) & ⊢ 𝑆 = sup(ran (𝑠 ∈ (𝒫 𝐴 ∩ Fin) ↦ (𝐺 Σg (𝐹 ↾ 𝑠))), ℝ*, < ) ⇒ ⊢ (𝜑 → (𝐺 tsums 𝐹) = {𝑆}) | ||
| Theorem | xrge0tsms2 24572 | Any finite or infinite sum in the nonnegative extended reals is convergent. This is a rather unique property of the set [0, +∞]; a similar theorem is not true for ℝ* or ℝ or [0, +∞). It is true for ℕ0 ∪ {+∞}, however, or more generally any additive submonoid of [0, +∞) with +∞ adjoined. (Contributed by Mario Carneiro, 13-Sep-2015.) |
| ⊢ 𝐺 = (ℝ*𝑠 ↾s (0[,]+∞)) ⇒ ⊢ ((𝐴 ∈ 𝑉 ∧ 𝐹:𝐴⟶(0[,]+∞)) → (𝐺 tsums 𝐹) ≈ 1o) | ||
| Theorem | metdcnlem 24573 | The metric function of a metric space is always continuous in the topology generated by it. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐶 = (dist‘ℝ*𝑠) & ⊢ 𝐾 = (MetOpen‘𝐶) & ⊢ (𝜑 → 𝐷 ∈ (∞Met‘𝑋)) & ⊢ (𝜑 → 𝐴 ∈ 𝑋) & ⊢ (𝜑 → 𝐵 ∈ 𝑋) & ⊢ (𝜑 → 𝑅 ∈ ℝ+) & ⊢ (𝜑 → 𝑌 ∈ 𝑋) & ⊢ (𝜑 → 𝑍 ∈ 𝑋) & ⊢ (𝜑 → (𝐴𝐷𝑌) < (𝑅 / 2)) & ⊢ (𝜑 → (𝐵𝐷𝑍) < (𝑅 / 2)) ⇒ ⊢ (𝜑 → ((𝐴𝐷𝐵)𝐶(𝑌𝐷𝑍)) < 𝑅) | ||
| Theorem | xmetdcn2 24574 | The metric function of an extended metric space is always continuous in the topology generated by it. In this variation of xmetdcn 24575 we use the metric topology instead of the order topology on ℝ*, which makes the theorem a bit stronger. Since +∞ is an isolated point in the metric topology, this is saying that for any points 𝐴, 𝐵 which are an infinite distance apart, there is a product neighborhood around ⟨𝐴, 𝐵⟩ such that 𝑑(𝑎, 𝑏) = +∞ for any 𝑎 near 𝐴 and 𝑏 near 𝐵, i.e., the distance function is locally constant +∞. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐶 = (dist‘ℝ*𝑠) & ⊢ 𝐾 = (MetOpen‘𝐶) ⇒ ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐷 ∈ ((𝐽 ×t 𝐽) Cn 𝐾)) | ||
| Theorem | xmetdcn 24575 | The metric function of an extended metric space is always continuous in the topology generated by it. (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐾 = (ordTop‘ ≤ ) ⇒ ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐷 ∈ ((𝐽 ×t 𝐽) Cn 𝐾)) | ||
| Theorem | metdcn2 24576 | The metric function of a metric space is always continuous in the topology generated by it. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐾 = (topGen‘ran (,)) ⇒ ⊢ (𝐷 ∈ (Met‘𝑋) → 𝐷 ∈ ((𝐽 ×t 𝐽) Cn 𝐾)) | ||
| Theorem | metdcn 24577 | The metric function of a metric space is always continuous in the topology generated by it. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐾 = (TopOpen‘ℂfld) ⇒ ⊢ (𝐷 ∈ (Met‘𝑋) → 𝐷 ∈ ((𝐽 ×t 𝐽) Cn 𝐾)) | ||
| Theorem | msdcn 24578 | The metric function of a metric space is always continuous in the topology generated by it. (Contributed by Mario Carneiro, 5-May-2014.) (Revised by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝑋 = (Base‘𝑀) & ⊢ 𝐷 = (dist‘𝑀) & ⊢ 𝐽 = (TopOpen‘𝑀) & ⊢ 𝐾 = (topGen‘ran (,)) ⇒ ⊢ (𝑀 ∈ MetSp → (𝐷 ↾ (𝑋 × 𝑋)) ∈ ((𝐽 ×t 𝐽) Cn 𝐾)) | ||
| Theorem | cnmpt1ds 24579* | Continuity of the metric function; analogue of cnmpt12f 23391 which cannot be used directly because 𝐷 is not necessarily a function. (Contributed by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝐷 = (dist‘𝐺) & ⊢ 𝐽 = (TopOpen‘𝐺) & ⊢ 𝑅 = (topGen‘ran (,)) & ⊢ (𝜑 → 𝐺 ∈ MetSp) & ⊢ (𝜑 → 𝐾 ∈ (TopOn‘𝑋)) & ⊢ (𝜑 → (𝑥 ∈ 𝑋 ↦ 𝐴) ∈ (𝐾 Cn 𝐽)) & ⊢ (𝜑 → (𝑥 ∈ 𝑋 ↦ 𝐵) ∈ (𝐾 Cn 𝐽)) ⇒ ⊢ (𝜑 → (𝑥 ∈ 𝑋 ↦ (𝐴𝐷𝐵)) ∈ (𝐾 Cn 𝑅)) | ||
| Theorem | cnmpt2ds 24580* | Continuity of the metric function; analogue of cnmpt22f 23400 which cannot be used directly because 𝐷 is not necessarily a function. (Contributed by Mario Carneiro, 5-Oct-2015.) |
| ⊢ 𝐷 = (dist‘𝐺) & ⊢ 𝐽 = (TopOpen‘𝐺) & ⊢ 𝑅 = (topGen‘ran (,)) & ⊢ (𝜑 → 𝐺 ∈ MetSp) & ⊢ (𝜑 → 𝐾 ∈ (TopOn‘𝑋)) & ⊢ (𝜑 → 𝐿 ∈ (TopOn‘𝑌)) & ⊢ (𝜑 → (𝑥 ∈ 𝑋, 𝑦 ∈ 𝑌 ↦ 𝐴) ∈ ((𝐾 ×t 𝐿) Cn 𝐽)) & ⊢ (𝜑 → (𝑥 ∈ 𝑋, 𝑦 ∈ 𝑌 ↦ 𝐵) ∈ ((𝐾 ×t 𝐿) Cn 𝐽)) ⇒ ⊢ (𝜑 → (𝑥 ∈ 𝑋, 𝑦 ∈ 𝑌 ↦ (𝐴𝐷𝐵)) ∈ ((𝐾 ×t 𝐿) Cn 𝑅)) | ||
| Theorem | nmcn 24581 | The norm of a normed group is a continuous function. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ 𝑁 = (norm‘𝐺) & ⊢ 𝐽 = (TopOpen‘𝐺) & ⊢ 𝐾 = (topGen‘ran (,)) ⇒ ⊢ (𝐺 ∈ NrmGrp → 𝑁 ∈ (𝐽 Cn 𝐾)) | ||
| Theorem | ngnmcncn 24582 | The norm of a normed group is a continuous function to ℂ. (Contributed by NM, 12-Aug-2007.) (Revised by AV, 17-Oct-2021.) |
| ⊢ 𝑁 = (norm‘𝐺) & ⊢ 𝐽 = (TopOpen‘𝐺) & ⊢ 𝐾 = (TopOpen‘ℂfld) ⇒ ⊢ (𝐺 ∈ NrmGrp → 𝑁 ∈ (𝐽 Cn 𝐾)) | ||
| Theorem | abscn 24583 | The absolute value function on complex numbers is continuous. (Contributed by NM, 22-Aug-2007.) (Proof shortened by Mario Carneiro, 10-Jan-2014.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) & ⊢ 𝐾 = (topGen‘ran (,)) ⇒ ⊢ abs ∈ (𝐽 Cn 𝐾) | ||
| Theorem | metdsval 24584* | Value of the "distance to a set" function. (Contributed by Mario Carneiro, 14-Feb-2015.) (Revised by Mario Carneiro, 4-Sep-2015.) (Revised by AV, 30-Sep-2020.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ (𝐴 ∈ 𝑋 → (𝐹‘𝐴) = inf(ran (𝑦 ∈ 𝑆 ↦ (𝐴𝐷𝑦)), ℝ*, < )) | ||
| Theorem | metdsf 24585* | The distance from a point to a set is a nonnegative extended real number. (Contributed by Mario Carneiro, 14-Feb-2015.) (Revised by Mario Carneiro, 4-Sep-2015.) (Proof shortened by AV, 30-Sep-2020.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝐹:𝑋⟶(0[,]+∞)) | ||
| Theorem | metdsge 24586* | The distance from the point 𝐴 to the set 𝑆 is greater than 𝑅 iff the 𝑅-ball around 𝐴 misses 𝑆. (Contributed by Mario Carneiro, 4-Sep-2015.) (Proof shortened by AV, 30-Sep-2020.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ (((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝐴 ∈ 𝑋) ∧ 𝑅 ∈ ℝ*) → (𝑅 ≤ (𝐹‘𝐴) ↔ (𝑆 ∩ (𝐴(ball‘𝐷)𝑅)) = ∅)) | ||
| Theorem | metds0 24587* | If a point is in a set, its distance to the set is zero. (Contributed by Mario Carneiro, 14-Feb-2015.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝐴 ∈ 𝑆) → (𝐹‘𝐴) = 0) | ||
| Theorem | metdstri 24588* | A generalization of the triangle inequality to the point-set distance function. Under the usual notation where the same symbol 𝑑 denotes the point-point and point-set distance functions, this theorem would be written 𝑑(𝑎, 𝑆) ≤ 𝑑(𝑎, 𝑏) + 𝑑(𝑏, 𝑆). (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ (((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ (𝐴 ∈ 𝑋 ∧ 𝐵 ∈ 𝑋)) → (𝐹‘𝐴) ≤ ((𝐴𝐷𝐵) +𝑒 (𝐹‘𝐵))) | ||
| Theorem | metdsle 24589* | The distance from a point to a set is bounded by the distance to any member of the set. (Contributed by Mario Carneiro, 5-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ (((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋) ∧ (𝐴 ∈ 𝑆 ∧ 𝐵 ∈ 𝑋)) → (𝐹‘𝐵) ≤ (𝐴𝐷𝐵)) | ||
| Theorem | metdsre 24590* | The distance from a point to a nonempty set in a proper metric space is a real number. (Contributed by Mario Carneiro, 5-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) ⇒ ⊢ ((𝐷 ∈ (Met‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → 𝐹:𝑋⟶ℝ) | ||
| Theorem | metdseq0 24591* | The distance from a point to a set is zero iff the point is in the closure set. (Contributed by Mario Carneiro, 14-Feb-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝐴 ∈ 𝑋) → ((𝐹‘𝐴) = 0 ↔ 𝐴 ∈ ((cls‘𝐽)‘𝑆))) | ||
| Theorem | metdscnlem 24592* | Lemma for metdscn 24593. (Contributed by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐶 = (dist‘ℝ*𝑠) & ⊢ 𝐾 = (MetOpen‘𝐶) & ⊢ (𝜑 → 𝐷 ∈ (∞Met‘𝑋)) & ⊢ (𝜑 → 𝑆 ⊆ 𝑋) & ⊢ (𝜑 → 𝐴 ∈ 𝑋) & ⊢ (𝜑 → 𝐵 ∈ 𝑋) & ⊢ (𝜑 → 𝑅 ∈ ℝ+) & ⊢ (𝜑 → (𝐴𝐷𝐵) < 𝑅) ⇒ ⊢ (𝜑 → ((𝐹‘𝐴) +𝑒 -𝑒(𝐹‘𝐵)) < 𝑅) | ||
| Theorem | metdscn 24593* | The function 𝐹 which gives the distance from a point to a set is a continuous function into the metric topology of the extended reals. (Contributed by Mario Carneiro, 14-Feb-2015.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐶 = (dist‘ℝ*𝑠) & ⊢ 𝐾 = (MetOpen‘𝐶) ⇒ ⊢ ((𝐷 ∈ (∞Met‘𝑋) ∧ 𝑆 ⊆ 𝑋) → 𝐹 ∈ (𝐽 Cn 𝐾)) | ||
| Theorem | metdscn2 24594* | The function 𝐹 which gives the distance from a point to a nonempty set in a metric space is a continuous function into the topology of the complex numbers. (Contributed by Mario Carneiro, 5-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ 𝐾 = (TopOpen‘ℂfld) ⇒ ⊢ ((𝐷 ∈ (Met‘𝑋) ∧ 𝑆 ⊆ 𝑋 ∧ 𝑆 ≠ ∅) → 𝐹 ∈ (𝐽 Cn 𝐾)) | ||
| Theorem | metnrmlem1a 24595* | Lemma for metnrm 24599. (Contributed by Mario Carneiro, 14-Jan-2014.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ (𝜑 → 𝐷 ∈ (∞Met‘𝑋)) & ⊢ (𝜑 → 𝑆 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → 𝑇 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → (𝑆 ∩ 𝑇) = ∅) ⇒ ⊢ ((𝜑 ∧ 𝐴 ∈ 𝑇) → (0 < (𝐹‘𝐴) ∧ if(1 ≤ (𝐹‘𝐴), 1, (𝐹‘𝐴)) ∈ ℝ+)) | ||
| Theorem | metnrmlem1 24596* | Lemma for metnrm 24599. (Contributed by Mario Carneiro, 14-Jan-2014.) (Revised by Mario Carneiro, 4-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ (𝜑 → 𝐷 ∈ (∞Met‘𝑋)) & ⊢ (𝜑 → 𝑆 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → 𝑇 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → (𝑆 ∩ 𝑇) = ∅) ⇒ ⊢ ((𝜑 ∧ (𝐴 ∈ 𝑆 ∧ 𝐵 ∈ 𝑇)) → if(1 ≤ (𝐹‘𝐵), 1, (𝐹‘𝐵)) ≤ (𝐴𝐷𝐵)) | ||
| Theorem | metnrmlem2 24597* | Lemma for metnrm 24599. (Contributed by Mario Carneiro, 14-Jan-2014.) (Revised by Mario Carneiro, 5-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ (𝜑 → 𝐷 ∈ (∞Met‘𝑋)) & ⊢ (𝜑 → 𝑆 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → 𝑇 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → (𝑆 ∩ 𝑇) = ∅) & ⊢ 𝑈 = ∪ 𝑡 ∈ 𝑇 (𝑡(ball‘𝐷)(if(1 ≤ (𝐹‘𝑡), 1, (𝐹‘𝑡)) / 2)) ⇒ ⊢ (𝜑 → (𝑈 ∈ 𝐽 ∧ 𝑇 ⊆ 𝑈)) | ||
| Theorem | metnrmlem3 24598* | Lemma for metnrm 24599. (Contributed by Mario Carneiro, 14-Jan-2014.) (Revised by Mario Carneiro, 5-Sep-2015.) |
| ⊢ 𝐹 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑆 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝐽 = (MetOpen‘𝐷) & ⊢ (𝜑 → 𝐷 ∈ (∞Met‘𝑋)) & ⊢ (𝜑 → 𝑆 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → 𝑇 ∈ (Clsd‘𝐽)) & ⊢ (𝜑 → (𝑆 ∩ 𝑇) = ∅) & ⊢ 𝑈 = ∪ 𝑡 ∈ 𝑇 (𝑡(ball‘𝐷)(if(1 ≤ (𝐹‘𝑡), 1, (𝐹‘𝑡)) / 2)) & ⊢ 𝐺 = (𝑥 ∈ 𝑋 ↦ inf(ran (𝑦 ∈ 𝑇 ↦ (𝑥𝐷𝑦)), ℝ*, < )) & ⊢ 𝑉 = ∪ 𝑠 ∈ 𝑆 (𝑠(ball‘𝐷)(if(1 ≤ (𝐺‘𝑠), 1, (𝐺‘𝑠)) / 2)) ⇒ ⊢ (𝜑 → ∃𝑧 ∈ 𝐽 ∃𝑤 ∈ 𝐽 (𝑆 ⊆ 𝑧 ∧ 𝑇 ⊆ 𝑤 ∧ (𝑧 ∩ 𝑤) = ∅)) | ||
| Theorem | metnrm 24599 | A metric space is normal. (Contributed by Jeff Hankins, 31-Aug-2013.) (Revised by Mario Carneiro, 5-Sep-2015.) (Proof shortened by AV, 30-Sep-2020.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐽 ∈ Nrm) | ||
| Theorem | metreg 24600 | A metric space is regular. (Contributed by Mario Carneiro, 29-Dec-2016.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐽 ∈ Reg) | ||
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