{
  "abstract": "We prove RE-completeness of the quantum homomorphism problem parameterised by families of graphs derived from the classic metric association schemes. These include Kneser graphs, $q$-Kneser graphs, and the complements of Johnson, Grassmann, and Hamming graphs. Our proof develops a spectral method for establishing non-contextuality of quantum polymorphisms. It combines an equality analysis of Roberson's bound on the projective packing number in terms of Schrijver's theta with a structural argument inspired by Erdős-Ko-Rado theory.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.20678",
  "author_total": 5,
  "authors": [
    {
      "name": "Lorenzo Ciardo"
    },
    {
      "name": "Iris Hebbeker"
    },
    {
      "name": "Gideo Joubert"
    },
    {
      "name": "Jana Kreiß"
    },
    {
      "name": "Antoine Mottet"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3xd53qqxf5swz.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.20678",
  "fulltext_url": null,
  "id": "3xd53qqxf5swz",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.20678",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cs.CC"
    ],
    [
      "arxiv",
      "cs.DM"
    ],
    [
      "arxiv",
      "math.CO"
    ],
    [
      "arxiv",
      "math.OA"
    ],
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      "arxiv",
      "quant-ph"
    ],
    [
      "openalex",
      "1703|Advanced Graph Theory Research"
    ]
  ],
  "openalex": "W7213596284",
  "pdf_url": "https://arxiv.org/pdf/2609.20678",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-17",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/3xd53qqxf5swz.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:22:19Z",
      "native_id": "2609.20678",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.20678"
    }
  ],
  "subjects": [
    {
      "field": "mathematics",
      "origin": "arxiv:math.OA",
      "subfield": "analysis-pdes"
    },
    {
      "field": "mathematics",
      "origin": "arxiv:math.CO",
      "subfield": "combinatorics"
    },
    {
      "field": "physics",
      "origin": "arxiv:quant-ph",
      "subfield": "quantum"
    }
  ],
  "title": "Schrijver-Delsarte rigidity in association schemes and undecidability of quantum graph homomorphism",
  "title_text": "Schrijver-Delsarte rigidity in association schemes and undecidability of quantum graph homomorphism",
  "type": "preprint",
  "updated_at": "2026-10-30T12:22:23Z",
  "url": "https://research.draconitic.com/paper/3xd53qqxf5swz",
  "venue": "arXiv",
  "versions": []
}