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arXiv · 2608.21206

No PUN Intended: Plausible Unknown Names for Person-Centred LLM Evaluation

Dimitri Staufer·David Hartmann·Ibrahim Baroud
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Abstract

Person names are widely used as prompt variables in LLM evaluations of factuality, privacy leakage, bias and abstention, but when a name's evidential status is uncontrolled, measurements may conflate memorisation, retrieval, name priors and wrong-person attribution. We operationalise an unknown name as one with plausible First-Last form, no indexed full-name evidence, and no ambiguity signals under a documented validation run, and introduce PUN (Plausible Unknown Names), a protocol for constructing and validating such names, combining Wikidata-derived components, web-enabled LLM screening, and controlled search revalidation. We report acceptance rate, reproducibility, ablations, and a 204-participant human study, finding accepted names are more name-like than controls while participants recover person evidence in only 3% of cases. We release 300 names with comparison controls.

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Dimitri Staufer, David Hartmann, Ibrahim Baroud. 2026-08-21. No PUN Intended: Plausible Unknown Names for Person-Centred LLM Evaluation. https://arxiv.org/abs/2608.21206

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