Home › Entities › hausdorff_space › Sorgenfrey line

Sorgenfrey line

real line endowed with the lower limit topology
Thing hausdorff_space Q117921997
Press Enter · cited answer in seconds

Sorgenfrey line

Summary

Sorgenfrey line is a Hausdorff space[1]. It has Wikipedia articles in 8 language editions, a strong signal of global cultural recognition.[2]

Key Facts

  • Sorgenfrey line's instance of is recorded as Hausdorff space[3].
  • Sorgenfrey line's instance of is recorded as perfectly normal space[4].
  • Sorgenfrey line's instance of is recorded as separable space[5].
  • Sorgenfrey line's instance of is recorded as first-countable space[6].
  • Sorgenfrey line's instance of is recorded as Lindelöf space[7].
  • Sorgenfrey line's instance of is recorded as strongly zero-dimensional Tychonoff space[8].
  • Robert Sorgenfrey is named after Sorgenfrey line[9].
  • Sorgenfrey line comprises lower limit topology[10].
  • Sorgenfrey line's underlying structure is recorded as set of real numbers[11].

Body

Definition and Type

Recorded instance of include Hausdorff space[3], perfectly normal space[4], separable space[5], first-countable space[6], Lindelöf space[7], and strongly zero-dimensional Tychonoff space[8].

Origins

Robert Sorgenfrey is named after Sorgenfrey line[9].

Use and Application

Sorgenfrey line comprises lower limit topology[10].

Why It Matters

Sorgenfrey line has Wikipedia articles in 8 language editions, a strong signal of global cultural recognition.[2]

References

Programmatic citations — every numbered marker resolves to a verifiable graph row below.

Direct Wikidata claims

  1. [3] ↑ . wikidata.org.
  2. [4] ↑ . wikidata.org.
  3. [5] ↑ . wikidata.org.
  4. [6] ↑ . wikidata.org.
  5. [7] ↑ . wikidata.org.
  6. [8] ↑ . wikidata.org.
  7. [9] ↑ . wikidata.org.
  8. [10] ↑ . wikidata.org.
  9. [11] ↑ . wikidata.org.

Class ancestry

  1. [1] ↑ . Wikidata. wikidata.org.

Aggregate / graph-position facts

  1. [2] ↑ . Wikidata sitelinks. wikidata.org.

📑 Cite this page

Use these citations when quoting this entity in research, articles, AI prompts, or wherever provenance matters. We aggregate Wikidata + Wikipedia + authoritative open-data sources; the stitched, scored, cross-referenced view is what 4ort.xyz contributes.

APA 4ort.xyz Knowledge Graph. (2026). Sorgenfrey line. Retrieved May 3, 2026, from https://4ort.xyz/entity/sorgenfrey-line
MLA “Sorgenfrey line.” 4ort.xyz Knowledge Graph, 4ort.xyz, 3 May. 2026, https://4ort.xyz/entity/sorgenfrey-line.
BibTeX @misc{4ortxyz_sorgenfrey-line_2026, author = {{4ort.xyz Knowledge Graph}}, title = {{Sorgenfrey line}}, year = {2026}, url = {https://4ort.xyz/entity/sorgenfrey-line}, note = {Accessed: 2026-05-03}}
LLM prompt According to 4ort.xyz Knowledge Graph (aggregator of Wikidata, Wikipedia, and authoritative open-data sources): Sorgenfrey line — https://4ort.xyz/entity/sorgenfrey-line (retrieved 2026-05-03)

Canonical URL: https://4ort.xyz/entity/sorgenfrey-line · Last refreshed:

Edit History

Rolling log of changes to this entity's Wikidata record. Values shown reflect the current state of each edited property — follow the history link to see the precise diff for any edit.

  1. 7d ago · Charp238 · 2026-07-11 view diff on Wikidata ↗
    Underlying structure(s) → set of real numbers
    Aliases → —
    Named after → —
    Instance of → Hausdorff space, perfectly normal space, separable space +3
    + 6 other properties edited (see Wikidata diff for full list)
    "/* wbsetclaim-create:2||1 */ [[Property:P2534]]: U\in\mathcal T(\mathbb R_\mathrm{Sorg}) \iff \exists a_i\in\mathbb R,\;b_i\in\mathbb R\;i\in I)\colon U=\bigcup_{i\in I}[a_i,b_i)"
Live feed via Wikidata EventStreams. New edits appear within minutes of being made on Wikidata.