TheoremDB

Problem packetResearch packetR924

R924Sourced evidence

Current status and unresolved remainder

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Authored summary

UNKNOWN as of 2026-07-31. A 2024 specialist lecture still lists Ostrovskii's 2005 question as an open problem. Dantas, Jung, and Martinez-Cervantes prove new sufficient conditions for non-norm-attaining operators in 2021, without resolving the remaining separable reflexive spaces lacking the relevant approximation properties. Construct an infinite-dimensional real or complex Banach space X and prove that every T in L(X) attains its norm, or prove that every infinite-dimensional real or complex Banach space admits a bounded self-operator that fails to attain its norm.

The record cites sources for its explanation.

Recorded status: reported

Recorded scope: No scope is recorded.

Originating problem: An infinite-dimensional Banach space where every operator attains its norm

Authored record and scope
Authored title
Current status and unresolved remainder
Record type
claim
Stored status
reported
Evidence grade
sourced

2Authored explanation

UNKNOWN as of 2026-07-31. A 2024 specialist lecture still lists Ostrovskii's 2005 question as an open problem. Dantas, Jung, and Martinez-Cervantes prove new sufficient conditions for non-norm-attaining operators in 2021, without resolving the remaining separable reflexive spaces lacking the relevant approximation properties.

A complete resolution must satisfy this condition: Construct an infinite-dimensional real or complex Banach space X and prove that every T in L(X) attains its norm, or prove that every infinite-dimensional real or complex Banach space admits a bounded self-operator that fails to attain its norm.

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Replay material: source only

3Evidence

Replay package: source only

A verification source is cited. This record has no executable replay attached.

Verification source: mathoverflow.net ↗, See dataset.references[0] for the exact external source and locator.

4How it connects

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Recorded for

Machine-readable record

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  "ref": "R924",
  "content_hash": null,
  "slug": "all-operators-norm-attaining-banach-space-claim-status-20260731",
  "type": "claim",
  "title": "Current status and unresolved remainder",
  "summary": "UNKNOWN as of 2026-07-31. A 2024 specialist lecture still lists Ostrovskii's 2005 question as an open problem. Dantas, Jung, and Martinez-Cervantes prove new sufficient conditions for non-norm-attaining operators in 2021, without resolving the remaining separable reflexive spaces lacking the relevant approximation properties. Construct an infinite-dimensional real or complex Banach space X and prove that every T in L(X) attains its norm, or prove that every infinite-dimensional real or complex Banach space admits a bounded self-operator that fails to attain its norm.",
  "relevance": "For all operators norm attaining banach space, pins the dated research frontier: UNKNOWN as of 2026-07-31. A 2024 specialist lecture still lists Ostrovskii's 2005 question as an open problem. Dantas, Jung, and Martinez-Cervantes prove new sufficient conditions for non-norm-attaining operators in 2021, without resolving the remaining separable reflexive spaces lacking the.",
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  "body": "UNKNOWN as of 2026-07-31. A 2024 specialist lecture still lists Ostrovskii's 2005 question as an open problem. Dantas, Jung, and Martinez-Cervantes prove new sufficient conditions for non-norm-attaining operators in 2021, without resolving the remaining separable reflexive spaces lacking the relevant approximation properties.\n\nA complete resolution must satisfy this condition: Construct an infinite-dimensional real or complex Banach space X and prove that every T in L(X) attains its norm, or prove that every infinite-dimensional real or complex Banach space admits a bounded self-operator that fails to attain its norm.",
  "status": "reported",
  "evidence_grade": "sourced",
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  "reproduction": {
    "schema": "theoremdb-reproduction-v1",
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    "citation": {
      "url": "https://mathoverflow.net/questions/232291/do-there-exist-infinite-dimensional-banach-spaces-in-which-every-bounded-linear",
      "locator": "See dataset.references[0] for the exact external source and locator."
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    "locator": "See dataset.references[0] for the exact external source and locator."
  },
  "models": [],
  "relations": [
    {
      "slug": "R923",
      "title": "Resolve the stated acceptance condition",
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6Provenance

View source, identifiers, and projection details

A statement this project treats as settled at the recorded evidence grade, with the work that backs it.

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