Two nets, three centuries apart, catching different ghosts

Claim (verbatim)

If the leishu are preservation filters, then two encyclopedias compiled 359 years apart should preserve measurably different dead books, because the pool of what was still quotable had itself thinned between them. The Yiwen leiju (藝文類聚, 624, Ouyang Xun, 100 juan, on the order of 1,400 cited sources) drew on a Tang imperial library that still held Six-Dynasties collections in bulk; the Taiping yulan (太平御覽, 983) drew on a Song library after the late-Tang and Five-Dynasties destructions had run their course. So the set of lost works recoverable only from the earlier net should be substantial and non-overlapping with the later net: the Yiwen leiju should be the sole surviving quotation-home for a body of sources the Taiping yulan no longer cites at all, because those sources were already gone by 983. Prediction restated: at least one in eight of the Yiwen leiju's distinct cited titles is absent from the Taiping yulan's citations entirely, and a majority of those earlier-only titles have no independent survival. The two encyclopedias are not one filter run twice but two filters over a shrinking pool, and the difference between their catches is a direct readout of what died in the intervening three centuries.

Prediction clause (verbatim)

Prediction: intersecting the two encyclopedias' attributed cited-title sets, at least one in eight of the Yiwen leiju's (藝文類聚) distinct cited titles will be absent from the Taiping yulan's (太平御覽) citations entirely, and of those Yiwen-leiju-only titles a majority will have no independent full-text survival (primary clause: the >=1-in-8 Yiwen-leiju-only share of its distinct cited titles; the verdict follows it); titles are matched on normalized forms to guard against abbreviation variance, and the test voids for coverage if fewer than 800 distinct titles resolve on each side.

Kill-dataset (verbatim)

Kill: the Chinese Text Project (ctext.org) full texts of the Yiwen leiju (藝文類聚) and the Taiping yulan (太平御覽), extracting and normalizing each work's attributed cited-title set, computing the set difference, and scoring the survival of the earlier-only titles.

Novelty / leakage triage

anticipated in the literature — this exact test has never been run

Both encyclopedias' cited-source pools are studied as preservation filters (Hu Daojing), and the qualitative claim that the earlier Tang net caught Six-Dynasties collections the Song net had already lost is plausible received wisdom. But the primary clause is a citation-set geometry — the >=1-in-8 Yiwen-leiju-only share of its distinct cited titles under the two encyclopedias' set-difference, with survival scored on the earlier-only remainder — and no published work computes that intersection as posed. This is new set arithmetic over in-print materials: adjacent. The nearest prior art characterizes each filter but has not differenced them.

• 胡道靜 (Hu Daojing), 中國古代的類書 (Beijing: Zhonghua shuju, 1982)
• The Yiwen leiju and Taiping yulan 引用書目 (cited-book bibliographies), printed with each text

Predictions

No prediction registered yet.