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    "headline": "A World Model Should Forget What Stopped Being True",
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    "dek": "Differential retention separates permanent invariants from instance facts that should be revised quickly.",
    "summary": "Differential retention separates permanent invariants from instance facts that should be revised quickly.",
    "body_text": "A position paper argues that ordinary continual-learning scores misclassify useful revision as catastrophic forgetting when the environment itself changes. It proposes testing invariant knowledge, such as physics and object permanence, separately from revision latency for mutable facts. The metric is a framework proposal rather than evidence from a new trained model.",
    "why_it_matters": "Differential retention separates permanent invariants from instance facts that should be revised quickly.",
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      "title": "arXiv preprint 2610.03713",
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