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    "story_id": "mp-2026-09-11-007",
    "source_story_id": "tmp-story-unlearning-checkpoint-audit",
    "edition_id": "mp-2026-09-11-morning-0064",
    "edition_url": "https://themachinepress.com/edition/2026-09-11",
    "position": 7,
    "story_type": "dispatch",
    "section": "benchmarks-evals",
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    "headline": "Forty-Seven Unlearning Checkpoints Moved Without Changing a Weight",
    "slug": "forty-seven-unlearning-checkpoints-moved-without-changing-a-weight",
    "dek": "Refitting batch-normalization statistics shifted published measurements beyond seed spread in 47 of 221 released checkpoints.",
    "summary": "Refitting batch-normalization statistics shifted published measurements beyond seed spread in 47 of 221 released checkpoints.",
    "body_text": "An unlearning verdict can depend on batch-normalization statistics that are shipped with the model but not written by gradient descent. At bit-identical weights, refitting those statistics on retained data moved 47 of 221 released checkpoints beyond the variability shown by their release seeds. Twelve published verdicts crossed their decision line; four exceeded a measured recalibration budget and two did so on every replicate. Swapping retained for removed records inside a fixed fitting pool barely moved the result, arguing against leftover removed data as the cause. The audit applies to batch-normalized vision models and calls for releases to state the fitting convention beside each number.",
    "why_it_matters": "Refitting batch-normalization statistics shifted published measurements beyond seed spread in 47 of 221 released checkpoints.",
    "limitations": [
      "An unlearning verdict can depend on batch-normalization statistics that are shipped with the model but not written by gradient descent."
    ],
    "importance": 8,
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    "first_published_at": "2026-09-11T09:00:00.000-04:00",
    "modified_at": "2026-09-11T09:00:00.000-04:00",
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        "text": "Refitting batch-normalization statistics shifted published measurements beyond seed spread in 47 of 221 released checkpoints.",
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        "qualification": "An unlearning verdict can depend on batch-normalization statistics that are shipped with the model but not written by gradient descent."
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    "tags": [
      "machine unlearning",
      "model audits",
      "reproducibility"
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    "image_url": null,
    "corrections": []
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  "sources": [
    {
      "source_id": "source-2026-09-11-007",
      "title": "arXiv preprint 2609.11490",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.11490",
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      "published_at": "2026-09-10T08:57:14.000-04:00",
      "accessed_at": "2026-09-11T08:25:00.000-04:00",
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  "publisher": {
    "name": "The Machine Press",
    "url": "https://themachinepress.com",
    "description": "A daily newspaper for the age of artificial intelligence."
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  "cite_this_report": {
    "title": "Forty-Seven Unlearning Checkpoints Moved Without Changing a Weight",
    "publisher": "The Machine Press",
    "published_at": "2026-09-11T09:00:00.000-04:00",
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