---
conjecture: r2-edh-b1-07
family: codex
model: "gpt-5.6-sol (codex-cli 0.144.0-alpha.4, ChatGPT-subscription auth)"
model_stamp_corrected: "2026-08-07 — archives were first written stamped gpt-5.5 by a runner bug (the stamper read config.toml's default instead of the -m flag actually passed). The calls themselves ran on gpt-5.6-sol throughout; only the label was wrong. Corrected in place, noted here rather than silently."
received: 2026-08-07
template: PROMPT_TEMPLATE_v1.md sha256 4344aabfacfe88362c56d89b6c89d594a7bf3a221e18a16b0e351482447e512f
rivals_parsed: 3
validation: VALID
---

{
  "rivals": [
    {
      "mechanism": "The apparent floor may be a mechanical occupancy effect created by conditioning on at least 150 genre-typed records. If eight or more genre labels have appreciable corpus-wide frequencies, samples of that size will almost inevitably contain them even when province has no causal effect on genre breadth.",
      "why_it_explains_the_same_evidence": "Both alphabetical halves were drawn from the same fixed 41-label corpus and subjected to the same typed-row threshold. Consequently, the training minimum of 11 and holdout minimum of 14 could both be ordinary outcomes of sampling common labels many times, with their difference arising from sample sizes and random composition rather than a provincial breadth floor.",
      "named_confounds": [
        "minimum-support conditioning on genre-typed rows",
        "sample-size or denominator effect",
        "global genre-frequency imbalance",
        "eligibility selection effect"
      ],
      "discriminating_test": {
        "description": "Preserve every province's eligible typed-row count, randomly permute genre labels among all records, and repeatedly recompute province-level diversity and the minimum across each split. Also rarefy every eligible province to exactly 150 typed rows. Compare the observed minima and failure count with their permutation distributions.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The rival is favored if zero provinces below eight and minima around 11-14 are common under permutation, and if rarefied provincial diversity is almost entirely predicted by pooled genre frequencies rather than province identity."
      }
    },
    {
      "mechanism": "Province totals may acquire high diversity by pooling inscriptions across many settlements and centuries. The floor would then be an artifact of taking the union of heterogeneous local and temporal assemblages, rather than evidence that any coherent provincial inscription-producing population was broadly distributed across genres.",
      "why_it_explains_the_same_evidence": "Support-qualified provinces are especially likely to contain records from numerous sites and periods, each contributing different genres. This union process operates throughout EDH, so an alphabetical split would reproduce it in both training and holdout provinces and could readily place every aggregated total above eight.",
      "named_confounds": [
        "administrative-unit aggregation",
        "spatial pooling across findspots",
        "temporal pooling across centuries",
        "modifiable areal unit effect"
      ],
      "discriminating_test": {
        "description": "Using EDH findspot and dating fields, partition each eligible province into spatially compact site groups and fixed temporal bands, retaining strata with at least 150 typed rows. Recompute diversity within those strata and model diversity against the number of site-period cells while controlling for typed-row count.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The rival is favored if many support-qualified site-period strata fall below eight and provincial diversity is explained mainly by the number of pooled site-period cells. A genuine support-based provincial breadth floor should be substantially more robust within comparably supported coherent strata."
      }
    },
    {
      "mechanism": "The diversity floor may result from mixing bibliographic, excavation, or cataloguing-source batches with different selection and typing profiles. Provinces large enough to reach 150 typed records may usually combine several such batches, whose union supplies many genre labels even if each source batch is narrow.",
      "why_it_explains_the_same_evidence": "A corpus-wide ingestion process would affect provinces in both alphabetical halves. If eligible provinces generally aggregate multiple publications or cataloguing campaigns, source mixing could produce the observed minima of 11 and 14 without requiring a province-level vocabulary-breadth floor.",
      "named_confounds": [
        "bibliographic-source mixture",
        "cataloguing-batch heterogeneity",
        "source-specific inclusion criteria",
        "data-entry classification practice"
      ],
      "discriminating_test": {
        "description": "Group records by primary publication, excavation corpus, or cataloguing batch; identify province-source strata with at least 150 typed rows; and recompute genre diversity within single-source strata. Then fit a model comparing the predictive effects of typed-row count and number of contributing sources, optionally after harmonizing demonstrably equivalent labels.",
        "computable_on_held_data": true,
        "what_result_favors_rival": "The rival is favored if support-qualified single-source strata frequently have fewer than eight genres, while diversity rises strongly with the number of contributing sources and materially declines after source-aware label harmonization."
      }
    }
  ],
  "no_viable_rival": false,
  "notes": "The alphabetical holdout limits province-specific overfitting but does not independently test mechanisms that operate corpus-wide through thresholding, aggregation, or shared cataloguing processes."
}
