{
  "abstract": "Machine-learning screens of metal–organic frameworks (MOFs) for CO2 capture increasingly report the validation protocol that produced a score, and topology hold-out has become the standard stricter alternative to random splitting. Prior work already reads topology hold-out as a combined structural and chemical distribution shift; this work measures the size of the chemistry that the split withholds. On the hypothetical-MOF library hMOF (324,426 structures), 74.7% of coarse-grained chemical compositions occur in a single topology, accounting for 61.3% of structures, and seven of eleven topologies leave every structure without a chemical counterpart in training. On the one usable chemistry-matched pair (pcu ↔nbo), removing the partner topology raised nbo-side MAE by 70.0% while a size-matched control did not, and removing only the shared-composition partner rows improved pcu-side MAE, so partner coverage is direction-dependent rather than uniformly beneficial. A chemistry-key hold-out produces only 21.1% of the topology hold-out's R2 decrease, so the support loss is real but does not translate proportionally into performance loss. Across five independently redrawn 25,000-sample support sets, the top-1% hit rate fell from 50.4% to 19.3% under topology-grouped validation. A support audit in ARC-MOF, which is partly dependent on hMOF and uses different composition keys, confirms strong coupling under bounded sensitivity rather than as an independent replication. We retain topology hold-out as a stress test while recommending that groupedsplit reports disclose their chemical support, deployment-relevant aggregation and ranking performance.",
  "abstract_shown": true,
  "affiliations": [
    "College of Chemical Engineering",
    "Nanjing Tech University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Tao Wang",
      "orcid": "0009-0005-2334-4636"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8haf58a86jbxy.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15010923/v1",
  "fulltext_url": null,
  "id": "8haf58a86jbxy",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010923/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1604|Metal-Organic Frameworks: Synthesis and Applications"
    ]
  ],
  "openalex": "W7222415650",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15010923/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-23",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/8haf58a86jbxy.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:26Z",
      "native_id": "10.26434/chemrxiv.15010923",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010923/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:1604|Metal-Organic Frameworks: Synthesis and Applications",
      "subfield": "inorganic"
    }
  ],
  "title": "What topology hold-out removes—and what it does not",
  "title_text": "What topology hold-out removes—and what it does not",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:26Z",
  "url": "https://research.draconitic.com/paper/8haf58a86jbxy",
  "venue": "ChemRxiv",
  "versions": []
}