伊敷喜斗のホームページ

Yoshito Ishiki's Home Page

Yoshito Ishiki. A mathematician.
I'm interested in metric geometry and general topology, or topological metric geometry.

伊敷喜斗．数学者．距離空間の幾何学を研究している数学者です．
興味：距離空間の幾何学と一般位相幾何学, もしくは位相的距離幾何学.

He/him.

E-mail: ishiki-yoshito[at mark]tmu.ac.jp
or
yoshito.ishiki[at mark]alum.riken.jp

Current Position: Postdoctoral researcher of Tokyo Metropolitan University.

現在の身分: 東京都立大学 特別研究員 (雇用PD) (学振PD採用者)

Links to Research map
Link to Google Scholar.
Link to GitHub

Research interests

研究テーマ

Recent situation

近況

My recent papers

最近の私の論文

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スクロールすると過去の項目を表示できます．

  1. 9 September 2026 — Preprint: 2026年9月9日 — プレプリント： The topology of Gromov–Hausdorff space.
  2. 4 September 2026 — Preprint: 2026年9月4日 — プレプリント： A counterexample to Scottish Book Problem 155.
  3. 20 August 2026, arXiv:2608.19618, Borelness of Moduli Spaces of Metrics Implies Separability.
    This is joint work with Tomoki Uda. We proved that if the space of compatible metrics on a metrizable space is Borel, then the underlying space is separable.
  4. 17 August 2026, arXiv:2608.16169, Absolute Borel Complexity of Moduli Spaces of Ultrametrics.
    I studied the absolute Borel complexity and complete metrizability of spaces of bounded compatible ultrametrics.
  5. 14 July 2026, arXiv:2607.12528, Algebraic structures on non-Archimedean Urysohn universal metric spaces.
    I investigated valued-field structures on Urysohn universal ultrametric spaces.
  6. June/2026. My paper "An interpolation of metrics and spaces of metrics" is published in Topology and its Applications, and became Open Access ( link ).
  7. My paper "Spaces of metrics are Baire" became Open Access ( link ).
  8. The joint work with Katsuhisa Koshino "On isometric universality of spaces of metrics" is published in Topology and its Applications ( link ).
  9. My paper "Spaces of metrics are Baire" is published in Topology and its Applications ( link ).
  10. My paper "Characterization of Urysohn universal ultrametric spaces" is published in AGMS (link).
  11. 27th September/2024, arXiv:2409.17701 This is a joint work with Katsuhisa Koshino. We researched isometric universality of spaces of metrics. For examples, we prove that the space of metrics on the Cantor set admits an isometric embedding from arbitrary compact metric spaces.
  12. I am writing a manuscript titled "A survey on comeager subsets in spaces of metrics" for submitting to RIMS Kôkyûroku as an article based on my talk in "RIMS symposium (open), General topology and related fields, in June 2024".
  13. 4th July/2024, arXiv:2407.03030 , An isometric extensor of metrics.
    For a metrizable space, and its closed subset, an extensor of metrics is defined as a map from the space of metrics on the closed subset into the space of metrics on the space, which actually extends metrics. I constructed an extensor of metrics, which preserving the supremum metrics on spaces of metrics.
  14. Feb/2024, arXiv:2402.04565 , Spaces of metrics are Baire.
    I proved that, for an arbitrary metrizable space, the space of metrics on the space is Baire with respect to the uniform topology.

CV

経歴

Education

学歴

Employment

職歴

Awards

受賞歴

Lecture Notes

講義ノート

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Talks

研究発表

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Papers

論文

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Memos/Notes

メモ/ノート

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Links to preprints

  1. arXiv:1710.08190 , Quasi-symmetric invariant properties of Cantor metric spaces
  2. arXiv:1911.07455 , On the Assouad dimension and convergence of metric spaces
  3. arXiv:1911.10775 , A characterization of metric subspaces of full Assouad dimension
  4. arXiv:2003.13227 , An interpolation of metrics and spaces of metrics
  5. arXiv:2008.10209 , An embedding, an extension, and an interpolation of ultrametrics
  6. arXiv:2104.12450 , On dense subsets in spaces of metrics
  7. arXiv:2108.06970 , Branching geodesics of the Gromov--Hausdorff distance
  8. arXiv:2110.01881 , Fractal dimensions in the Gromov--Hausdorff space
  9. arXiv:2111.08199 , Continua in the Gromov--Hausdorff space
  10. arXiv:2112.05345 , Metric trees in the Gromov--Hausdorff space
  11. arXiv:2206.10778 , Simultaneous extensions of metrics and ultrametrics of high power
  12. arXiv:2207.12765 , On comeager sets of metrics whose ranges are disconnected
  13. arXiv:2207.12905 , Extending proper metrics
  14. arXiv:2210.02170 , Strongly rigid metrics in spaces of metrics
  15. arXiv:2212.13409 , A factorization of metric spaces
  16. arXiv:2302.00305 , Constructions of Urysohn universal ultrametric spaces
  17. arXiv:2302.00306 , Uniqueness and homogeneity of non-separable Urysohn universal ultrametric spaces
  18. arXiv:2303.17471 , Characterizations of Urysohn universal ultrametric spaces
  19. arXiv:2309.06704 , A non-Archimedean Arens--Eells isometric embedding theorem on valued fields
  20. arXiv:2402.04565 , Spaces of metrics are Baire
  21. arXiv:2407.03030 , An isometric extensor of metrics
  22. arXiv:2409.17701 , On isometric universality of spaces of metrics (joint work with Katsuhisa Koshino)
  23. arXiv:2607.12528 , Algebraic structures on non-Archimedean Urysohn universal metric spaces
  24. arXiv:2608.16169 , Absolute Borel Complexity of Moduli Spaces of Ultrametrics
  25. arXiv:2608.19618 , Borelness of Moduli Spaces of Metrics Implies Separability (joint work with Tomoki Uda)
  26. PDF, The topology of Gromov–Hausdorff space (details and citation)
  27. PDF A counterexample to Scottish Book Problem 155 (A modified version of AI-Assisted Research Report: A counterexample to Scottish Book Problem 155 details and citation; DOI: 10.5281/zenodo.22422011)

Links to my academic accounts

  1. Google Scholar
  2. ORCiD
  3. zbMATH
  4. Research map

Links to Web pages of mathematicians

Links to useful Web pages

Photos

写真

A real Cantor set in Wakoshi city, Saitama:

A real Cantor set in Saitama, which is a tree without leaves

Real Cantor sets in Hachioji city, Tokyo:

Real Cantor sets in Tokyo, which are trees without leaves