The twin reconstructed from its own echoes

Claim (verbatim)

The tannaitic halakhic midrashim on Exodus come in two recensions from rival schools: the Mekhilta de-Rabbi Ishmael, which survives intact and independently, and the Mekhilta de-Rabbi Shimon bar Yohai (Mekhilta de-Rashbi), which was lost as a standalone book and reassembled in the modern era - by D. Z. Hoffmann and then in the Epstein-Melamed critical edition (1955) - out of quotations embedded in later compilations, above all the thirteenth-to-fourteenth-century Yemenite Midrash ha-Gadol of David b. Amram al-Adani. The mechanism of loss dictates the shape of the recovery: a book reconstituted from a reservoir cannot be more complete than the reservoir chose to be, so the recovered Mekhilta de-Rashbi should not mirror the verse-coverage of its intact twin but should collapse toward wherever Midrash ha-Gadol and the other citing compilations happened to draw. Because those reservoirs quarried preferentially for halakhic and quotable matter, the reconstruction should thin out exactly where the intact Mekhilta is richest in non-legal narrative. Prediction restated: the reconstructed Mekhilta de-Rashbi covers substantially fewer distinct Exodus verses than the intact Mekhilta de-Rabbi Ishmael, with the shortfall concentrated in narrative pericopes - the fingerprint of a text known only through the filter that saved it, not through itself.

Prediction clause (verbatim)

Prediction: mapping each midrash's comments to their Exodus verse-anchors in Sefaria, the count of distinct Exodus verses treated in the reconstructed Mekhilta de-Rabbi Shimon bar Yochai will be under two-thirds (a ratio < 0.67) of the distinct verses treated in the intact Mekhilta de-Rabbi Yishmael, and the coverage gap will fall disproportionately in narrative (non-halakhic) sections rather than legal ones - primary clause: the < 0.67 reconstructed-to-intact distinct-verse-coverage ratio; the verdict follows it. The test voids for coverage if Sefaria's Mekhilta de-Rashbi is itself only partially digitized, in which case the Epstein-Melamed printed edition supplies the verse map.

Kill-dataset (verbatim)

Kill (partly not yet built): Sefaria's Mekhilta de-Rabbi Yishmael and Mekhilta de-Rabbi Shimon bar Yochai, aligning each comment to its Exodus verse-anchor and comparing distinct-verse coverage; where Sefaria's Rashbi text is incomplete, the Epstein-Melamed critical edition (1955) supplies the verse map and the Midrash ha-Gadol supplies the reservoir profile.

Novelty / leakage triage

already answered in the literature

The printed verse-maps already answer the primary clause - against it. The Epstein-Melamed edition (which rests substantially on Geniza leaves of the work itself, not only on Midrash ha-Gadol quotations) and the standard reference's coverage lists give the reconstructed Mekhilta de-Rashbi a span reaching Exodus 3 and 6 and running 12:1-24:10 plus the sabbath pericopes, while the intact Mekhilta de-R. Ishmael begins only at Ex 12:1 and ends at 23:19 (plus 31:12-17, 35:1-3); the reconstructed twin's distinct-verse extent is comparable to or greater than the intact one's. A competent reader derives from these printed maps, without touching Sefaria, that the < 0.67 reconstructed-to-intact coverage ratio fails - guaranteed list-arithmetic on published editions, in the exemplars' sense, with the leak running against the conjecture's expected direction.

Predictions