TheoremDB

Problem packetResearch packetR1738

R1738Sourced evidence

Strongest checked neighboring result

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Authored summary

The conjecture is proved for all hypergraphs when r≤3 and for intersecting hypergraphs when r≤5. For r=4 and r=5, Haxell and Scott prove τ(H)≤(r-ε)ν(H) for some ε>0. Further exact cases include maximum degree at most 2 and several strongly intersecting families.

The record cites sources for its explanation.

Recorded status: reported

Recorded scope: No scope is recorded.

Originating problem: Ryser’s conjecture for multipartite hypergraphs

Authored record and scope
Authored title
Strongest checked neighboring result
Record type
claim
Stored status
reported
Evidence grade
sourced

2Authored explanation

The conjecture is proved for all hypergraphs when r≤3 and for intersecting hypergraphs when r≤5. For r=4 and r=5, Haxell and Scott prove τ(H)≤(r-ε)ν(H) for some ε>0. Further exact cases include maximum degree at most 2 and several strongly intersecting families.

This leaves the following boundary unresolved: Prove the conjectured coefficient r-1 for arbitrary r-partite, r-uniform hypergraphs when r≥4, or give a counterexample. Even the intersecting case ν(H)=1 remains open for every r≥6. The 2025 counterexample to the stronger Lovász conjecture does not settle Ryser’s conjecture. Corpus searches found only unrelated Bruck-Ryser references and no equivalent TheoremDB target. The distinction is retained here so a restricted theorem, finite computation, or neighboring case is not presented as a solution of the full target.

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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: doi.org ↗, A. Clow, P. Haxell, and B. Mohar, A Counterexample to a Conjecture of Lovász, arXiv:2505.05339 (2025). Abstract and Introduction

4What was measured

5How it connects

Informs

Recorded for

Machine-readable record

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  "ref": "R1738",
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  "slug": "ryser-hypergraph-cover-conjecture-claim-literature-frontier",
  "type": "claim",
  "title": "Strongest checked neighboring result",
  "summary": "The conjecture is proved for all hypergraphs when r≤3 and for intersecting hypergraphs when r≤5. For r=4 and r=5, Haxell and Scott prove τ(H)≤(r-ε)ν(H) for some ε>0. Further exact cases include maximum degree at most 2 and several strongly intersecting families.",
  "relevance": "Locates the present research frontier immediately below Ryser’s conjecture for multipartite hypergraphs.",
  "relevance_source": "recorded",
  "body": "The conjecture is proved for all hypergraphs when r≤3 and for intersecting hypergraphs when r≤5. For r=4 and r=5, Haxell and Scott prove τ(H)≤(r-ε)ν(H) for some ε>0. Further exact cases include maximum degree at most 2 and several strongly intersecting families.\n\nThis leaves the following boundary unresolved: Prove the conjectured coefficient r-1 for arbitrary r-partite, r-uniform hypergraphs when r≥4, or give a counterexample. Even the intersecting case ν(H)=1 remains open for every r≥6. The 2025 counterexample to the stronger Lovász conjecture does not settle Ryser’s conjecture. Corpus searches found only unrelated Bruck-Ryser references and no equivalent TheoremDB target. The distinction is retained here so a restricted theorem, finite computation, or neighboring case is not presented as a solution of the full target.",
  "status": "reported",
  "evidence_grade": "sourced",
  "scope": null,
  "reproduction": {
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    "kind": "claim",
    "citation": {
      "url": "https://doi.org/10.48550/arXiv.2505.05339",
      "locator": "A. Clow, P. Haxell, and B. Mohar, A Counterexample to a Conjecture of Lovász, arXiv:2505.05339 (2025). Abstract and Introduction"
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  "source": {
    "url": "https://doi.org/10.48550/arXiv.2505.05339",
    "locator": "A. Clow, P. Haxell, and B. Mohar, A Counterexample to a Conjecture of Lovász, arXiv:2505.05339 (2025). Abstract and Introduction"
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  "relations": [
    {
      "slug": "R1739",
      "title": "Current status and exact unresolved remainder",
      "object_type": "claim",
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    {
      "slug": "ryser-hypergraph-cover-conjecture",
      "title": "ryser hypergraph cover conjecture",
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7Provenance

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

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