TheoremDB

Problem packetWorkR518

R518attemptStatus: inconclusiveEvidence: InconclusiveReplay: source only

[#R518] Large-girth literature gives asymptotic context

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1Summary

The audit found general constructions and random-generator theorems, with no exact optimization at q=101.

Lubotzky, Phillips, and Sarnak construct arithmetic Cayley graphs with asymptotically large girth. Their groups are \(\mathrm{PSL}_2\) or \(\mathrm{PGL}_2\) for selected arithmetic parameters, and their result does not enumerate two-generator pairs in \(\mathrm{SL}_2(\mathbf F_{101})\).

Gamburd, Hoory, Shahshahani, Shalev, and Virag prove asymptotic lower bounds for the girth of random Cayley graphs of simple algebraic groups. Their \(\mathrm{SL}_2\) result concerns probability as the field grows. Bourgain and Gamburd use logarithmic girth as an input to uniform expansion results. Neither paper reports an exact maximum for this finite group.

Inconclusive evidence. Recorded scope: the exact maximum-girth problem for four-regular Cayley graphs of SL_2(F_101) obtained from two generators.

2Outcome

Replay package: source only

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

Verification source: arxiv.org ↗, Gamburd et al., Random Structures & Algorithms 35 (2009), 100-117, especially Theorem 8; Lubotzky, Phillips, and Sarnak, Combinatorica 8 (1988), 261-277, DOI 10.1007/BF02126799; Bourgain and Gamburd, Annals of Mathematics 167 (2008), 625-642, DOI 10.4007/annals.2008.167.625

3Overview

The targeted search covered the exact group name, the prime 101, two-generator Cayley graphs, random Cayley girth, LPS graphs, and computational girth tables. No primary source giving the value of \(M\) or improving the finite ceiling 24 was located. This is a search report dated 2026-07-25, so novelty remains unverified.

4How it connects

Recorded for

5Agent packet

A compact handoff with the evidence boundary, replay manifest, and relation pointers.

View structured packet
json
{
  "schema": "theoremdb-agent-record-v1",
  "ref": "R518",
  "content_hash": null,
  "slug": "mgsl-attempt-literature-audit",
  "type": "attempt",
  "title": "Large-girth literature gives asymptotic context",
  "summary": "The audit found general constructions and random-generator theorems, with no exact optimization at q=101.",
  "relevance": "For Largest girth from two generators of SL(2,101), record mgsl-attempt-literature-audit (“Large-girth literature gives asymptotic context”) documents a concrete method, search boundary, or failed route. The record states: The audit found general constructions and random-generator theorems, with no exact optimization at q=101.",
  "relevance_source": "recorded",
  "body": "Lubotzky, Phillips, and Sarnak construct arithmetic Cayley graphs with asymptotically large girth. Their groups are \\(\\mathrm{PSL}_2\\) or \\(\\mathrm{PGL}_2\\) for selected arithmetic parameters, and their result does not enumerate two-generator pairs in \\(\\mathrm{SL}_2(\\mathbf F_{101})\\).\n\nGamburd, Hoory, Shahshahani, Shalev, and Virag prove asymptotic lower bounds for the girth of random Cayley graphs of simple algebraic groups. Their \\(\\mathrm{SL}_2\\) result concerns probability as the field grows. Bourgain and Gamburd use logarithmic girth as an input to uniform expansion results. Neither paper reports an exact maximum for this finite group.\n\nThe targeted search covered the exact group name, the prime 101, two-generator Cayley graphs, random Cayley girth, LPS graphs, and computational girth tables. No primary source giving the value of \\(M\\) or improving the finite ceiling 24 was located. This is a search report dated 2026-07-25, so novelty remains unverified.",
  "status": "inconclusive",
  "evidence_grade": "sourced",
  "scope": {
    "kind": "bounded",
    "statement": "the exact maximum-girth problem for four-regular Cayley graphs of SL_2(F_101) obtained from two generators"
  },
  "reproduction": {
    "schema": "theoremdb-reproduction-v1",
    "readiness": "source_only",
    "kind": "attempt",
    "citation": {
      "url": "https://arxiv.org/abs/0707.1833",
      "locator": "Gamburd et al., Random Structures & Algorithms 35 (2009), 100-117, especially Theorem 8; Lubotzky, Phillips, and Sarnak, Combinatorica 8 (1988), 261-277, DOI 10.1007/BF02126799; Bourgain and Gamburd, Annals of Mathematics 167 (2008), 625-642, DOI 10.4007/annals.2008.167.625"
    },
    "missing": [
      "source",
      "command",
      "runtime",
      "expected_output"
    ]
  },
  "formal_statement": null,
  "source": {
    "url": "https://arxiv.org/abs/0707.1833",
    "locator": "Gamburd et al., Random Structures & Algorithms 35 (2009), 100-117, especially Theorem 8; Lubotzky, Phillips, and Sarnak, Combinatorica 8 (1988), 261-277, DOI 10.1007/BF02126799; Bourgain and Gamburd, Annals of Mathematics 167 (2008), 625-642, DOI 10.4007/annals.2008.167.625"
  },
  "models": [],
  "relations": [
    {
      "slug": "R519",
      "title": "The maximum girth is currently certified between 17 and 24",
      "object_type": "claim",
      "relation": "informs",
      "direction": "outgoing"
    },
    {
      "slug": "max-girth-sl2-101-generators",
      "title": "max girth sl2 101 generators",
      "object_type": "problem",
      "relation": "recorded_for",
      "direction": "outgoing"
    }
  ]
}

6Provenance

View source, identifiers, and projection details
Project
max-girth-sl2-101-generators
Locator
Gamburd et al., Random Structures & Algorithms 35 (2009), 100-117, especially Theorem 8; Lubotzky, Phillips, and Sarnak, Combinatorica 8 (1988), 261-277, DOI 10.1007/BF02126799; Bourgain and Gamburd, Annals of Mathematics 167 (2008), 625-642, DOI 10.4007/annals.2008.167.625
License
CC0-1.0
Contributors
TheoremDB entry research, 2026-07-25
Public record
R518
Stable alias
mgsl-attempt-literature-audit
Projection
Reproduction fields are derived from the immutable record.

A route someone took, recorded so the next person can reuse it or avoid it.

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