AI-generated conjecture · a wager, not a finding
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The dictionary that shelters lost books
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Claim (verbatim)
The Sefer he-Arukh of Nathan b. Yehiel of Rome (completed c. 1101) is a talmudic dictionary, but for the history of loss it is a reliquary: to gloss a hard word Nathan quotes his sources, and those sources include geonic works, targumic and midrashic material, and "Yerushalmi" readings that no longer exist in the forms he had. The Arukh preserves, in passing and by lemma, fragments of a library that was still on Nathan's shelf in eleventh-century Rome and is now largely gone - including citations of the Palestinian Talmud that diverge from our text and quotations of geonic and midrashic works otherwise unattested. Mechanism: a lexicographer must quote to define, so a dictionary compiled at a given place and moment fossilizes whatever books were locally available, and when those books vanish the dictionary's citations become their last witness. The enumerable claim is that a substantial share of the Arukh's source-citations point to works or textual states not independently extant. Prediction restated: cataloguing the Arukh's attributed source-citations, a significant minority name works - geonic monographs, divergent Yerushalmi passages, lost midrashim - with no surviving independent full-text witness, making the dictionary a measurable reservoir of the lost.
Prediction clause (verbatim)
Prediction: enumerating the attributed source-citations in the Sefer he-Arukh and testing each for independent survival, more than one in eight (> 0.125) of the distinct cited works or textual states will have no surviving independent full-text witness - surviving, if at all, only as quotation - primary clause: the > 0.125 no-independent-witness share among distinct cited sources; the verdict follows it. A source counts as extant only on an independent full-text witness, not a later re-citation of its name; the test voids for coverage if fewer than 300 distinct source-citations can be extracted.
Kill-dataset (verbatim)
Kill (not yet built): Kohut's critical edition Aruch Completum (Arukh ha-Shalem, ed. Alexander Kohut) as the citation-extraction instrument - enumerate the Arukh's attributed source-citations and test each against Sefaria's open corpus and the standard critical editions for independent survival; runnable once the Arukh's citation apparatus is digitized and keyed.
Nobody has run this test. The kill-data is named above. If you can run it — or you know the paper that already settles it — claim the kill or submit the prior scholarship. Kills and prior scholarship are credited here, by name, as they come in.
Provenance
Run: Fresh agent generation · model: claude-fable-5
Fresh blind generation by claude-fable-5, 2026-07-17, Jewish text-culture wave instrument-anchored on the open Sefaria corpus and its cross-reference link data, with standard critical editions as controls: every kill names a real corpus and a countable operation (coverage maps, citation-formula counts, link-orphan shares, digest-fraction, recension divergence, citation-decay), thresholds far from 1 with explicit coverage guards distinguishing what Sefaria holds from what existed. Ground is CITATION-GEOMETRIC and disjoint from the 2026-07-10 w19 Jewish wave, which was material-culture-of-loss (colophons, parchment, genizah, masora, binding fragments): no material-culture re-posing here. Two candidates were dropped after a grep of all fresh packets: a Tosafot-density-by-tractate survival item (pre-empted by w02-philosophy #18, which already correlates per-folio Tosafot density with manuscript survival), and a piyyut liturgy-vs-anthology survival item (pre-empted by w01-literature #28 'Liturgy out-survives fame', keyed to Davidson's Thesaurus). The Mishneh Torah item here tests EXTERNAL source-attribution erasure vs the Tur (loss of source-geometry), deliberately distinct from minds-w02 #25, which tests the code's INTERNAL recall/promise cross-references. Two items are marked Kill (not yet built) where the deciding corpus (Kohut's Arukh apparatus; Lewin's parallel Iggeret recensions) is not yet digitized.
Novelty / leakage triage
anticipated in the literature — this exact test has never been run
Kohut's prolegomena to the Aruch Completum enumerate Nathan's sources, and the Arukh's standing as a reservoir of lost material is standard: Ginzberg's Geonica quarries it for lost geonic writings, and Lieberman's Yerushalmi studies exploit its divergent Yerushalmi lemmata. But the primary clause - more than one in eight distinct cited works or textual states without an independent full-text witness - requires adjudicating each source against the present corpus, where post-Kohut Geniza discoveries have moved items in both directions, and the individuation of 'textual states' is not fixed by any printed census. The enumeration is printed; the survival-share arithmetic against today's corpus is un-run.
- A. Kohut (ed.), Aruch Completum (Arukh ha-Shalem), 8 vols. (Vienna, 1878-1892), prolegomena on Nathan b. Yehiel's sources
- S. Krauss (ed.), Additamenta ad librum Aruch Completum (Vienna, 1937)
- L. Ginzberg, Geonica (New York: JTS, 1909)
- S. Lieberman, Ha-Yerushalmi Kiphshuto (Jerusalem, 1934)
Predictions
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