HomeTheorem List (p. 250 of 506)
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| Type | Label | Description |
|---|---|---|
| Statement | ||
| Theorem | iooretop 24901 | Open intervals are open sets of the standard topology on the reals . (Contributed by FL, 18-Jun-2007.) |
| ⊢ (𝐴(,)𝐵) ∈ (topGen‘ran (,)) | ||
| Theorem | icccld 24902 | 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 24903 | 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 24904 | 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 24905 | ℚ is dense in the standard topology on ℝ. (Contributed by NM, 1-Mar-2007.) |
| ⊢ ((cls‘(topGen‘ran (,)))‘ℚ) = ℝ | ||
| Theorem | cnmetdval 24906 | 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 24907 | 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 24908 | The absolute value metric is an extended metric. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ (abs ∘ − ) ∈ (∞Met‘ℂ) | ||
| Theorem | cnbl0 24909 | 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 24910* | 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 24911 | The complex number field is a metric space. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ ℂfld ∈ MetSp | ||
| Theorem | cnfldxms 24912 | The complex number field is a topological space. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ ℂfld ∈ ∞MetSp | ||
| Theorem | cnfldtps 24913 | The complex number field is a topological space. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ ℂfld ∈ TopSp | ||
| Theorem | cnfldnm 24914 | The norm of the field of complex numbers. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ abs = (norm‘ℂfld) | ||
| Theorem | cnngp 24915 | The complex numbers form a normed group. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ ℂfld ∈ NrmGrp | ||
| Theorem | cnnrg 24916 | The complex numbers form a normed ring. (Contributed by Mario Carneiro, 4-Oct-2015.) |
| ⊢ ℂfld ∈ NrmRing | ||
| Theorem | cnfldtopn 24917 | The topology of the complex numbers. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 = (MetOpen‘(abs ∘ − )) | ||
| Theorem | cnfldtopon 24918 | The topology of the complex numbers is a topology. (Contributed by Mario Carneiro, 2-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ (TopOn‘ℂ) | ||
| Theorem | cnfldtop 24919 | The topology of the complex numbers is a topology. (Contributed by Mario Carneiro, 2-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ Top | ||
| Theorem | cnfldhaus 24920 | The topology of the complex numbers is Hausdorff. (Contributed by Mario Carneiro, 8-Sep-2015.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ Haus | ||
| Theorem | unicntop 24921 | 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 24922 | 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 | cnn0opn 24923 | The set of nonzero complex numbers is open with respect to the standard topology on complex numbers. (Contributed by SN, 7-Oct-2025.) |
| ⊢ (ℂ ∖ {0}) ∈ (TopOpen‘ℂfld) | ||
| Theorem | zringnrg 24924 | The ring of integers is a normed ring. (Contributed by AV, 13-Jun-2019.) |
| ⊢ ℤring ∈ NrmRing | ||
| Theorem | remetdval 24925 | 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 24926 | 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 24927 | The absolute value metric is an extended metric. (Contributed by Mario Carneiro, 28-Aug-2015.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) ⇒ ⊢ 𝐷 ∈ (∞Met‘ℝ) | ||
| Theorem | bl2ioo 24928 | 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 24929 | 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 24930 | 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 24931 | 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 24932 | 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 24933 | ℚ is dense in ℝ. (Contributed by NM, 24-Aug-2007.) |
| ⊢ 𝐷 = ((abs ∘ − ) ↾ (ℝ × ℝ)) & ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ ((cls‘𝐽)‘ℚ) = ℝ | ||
| Theorem | blcvx 24934 | 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 24935 | The standard topology on the reals is Hausdorff. (Contributed by NM, 8-Mar-2007.) |
| ⊢ (topGen‘ran (,)) ∈ Haus | ||
| Theorem | tgqioo 24936 | 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 24937 | The standard topology on the reals is second-countable. (Contributed by Mario Carneiro, 21-Mar-2015.) |
| ⊢ (topGen‘ran (,)) ∈ 2ndω | ||
| Theorem | resubmet 24938 | 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 24939 | 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 24940 | 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 | tgioo4 24941 | The standard topology on the reals is a subspace of the complex metric topology. (Contributed by Glauco Siliprandi, 5-Feb-2022.) |
| ⊢ (topGen‘ran (,)) = ((TopOpen‘ℂfld) ↾t ℝ) | ||
| Theorem | tgioo3 24942 | 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 24943 | 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 24944 | 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 24945 | 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 24946 | 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 24947 | 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 24948 | 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 24949 | 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 24950 | 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 24951 | 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 24952 | 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 24953 | 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 24954 | 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 24955* | 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 24956 | 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 24957 | The complex numbers are a perfect space. (Contributed by Mario Carneiro, 26-Dec-2016.) |
| ⊢ 𝐽 = (TopOpen‘ℂfld) ⇒ ⊢ 𝐽 ∈ Perf | ||
| Theorem | iccntr 24958 | 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 24959* | Lemma for icccmp 24962. (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 24960* | Lemma for icccmp 24962. (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 24961* | Lemma for icccmp 24962. (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 24962 | 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 24963 | Lemma for reconn 24965. 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 24964* | Lemma for reconn 24965. (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 24965* | 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 24966 | Corollary of reconn 24965. The set of real numbers is connected. (Contributed by Jeff Hankins, 17-Aug-2009.) |
| ⊢ (topGen‘ran (,)) ∈ Conn | ||
| Theorem | iccconn 24967 | A closed interval is connected. (Contributed by Jeff Hankins, 17-Aug-2009.) |
| ⊢ ((𝐴 ∈ ℝ ∧ 𝐵 ∈ ℝ) → ((topGen‘ran (,)) ↾t (𝐴[,]𝐵)) ∈ Conn) | ||
| Theorem | opnreen 24968 | 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 24969 | 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 24970 | 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 24971* | 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 24972 | 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 24973 | 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 24974 | The metric function of an extended metric space is always continuous in the topology generated by it. In this variation of xmetdcn 24975 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 24975 | 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 24976 | 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 24977 | 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 24978 | 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 24979* | Continuity of the metric function; analogue of cnmpt12f 23802 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 24980* | Continuity of the metric function; analogue of cnmpt22f 23811 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 24981 | 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 24982 | 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 24983 | 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 24984* | 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 24985* | 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 24986* | 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 24987* | 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 24988* | 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 24989* | 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 24990* | 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 24991* | 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 24992* | Lemma for metdscn 24993. (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 24993* | 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 24994* | 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 24995* | Lemma for metnrm 24999. (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 24996* | Lemma for metnrm 24999. (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 24997* | Lemma for metnrm 24999. (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 24998* | Lemma for metnrm 24999. (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 24999 | 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 25000 | A metric space is regular. (Contributed by Mario Carneiro, 29-Dec-2016.) |
| ⊢ 𝐽 = (MetOpen‘𝐷) ⇒ ⊢ (𝐷 ∈ (∞Met‘𝑋) → 𝐽 ∈ Reg) | ||
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