Milan is the control group

Claim (verbatim)

Milan kept its rite. Alone among the great non-Roman Latin uses, the Ambrosian rite was never suppressed, and its chant survives in hundreds of complete, purpose-made, pitch-readable manuscripts - a fully notated tradition still indexable today. Set beside it, the suppressed repertories become legible as a controlled experiment in survival: Old Hispanic, Old Roman, Beneventan, and Gallican chant all had comparably large original repertories and comparably ancient roots, but each met suppression or displacement, and each survives as a near-nullity of readable melody. The only variable that separates Milan's plenitude from Leon's silence is the institutional fact of continuity: an unbroken rite generated an unbroken chain of purpose-made notated books, while a broken rite generated palimpsests, unheighted relics, and calendar cues. The mechanism is not the quality or antiquity of the music but whether an institution remained obligated to sing it and therefore to recopy it in current, readable notation. Milan is thus the counterfactual made visible - what Toledo or Benevento would look like in the databases had Rome not intervened. Prediction restated: the count of indexed, pitch-readable Ambrosian office chants exceeds the count of transcribable Old Hispanic melodies by more than two orders of magnitude, though the two rites' original repertories were of the same order of size.

Prediction clause (verbatim)

Prediction: the number of pitch-readable Ambrosian office chants recoverable from surviving notated Ambrosian antiphoners exceeds the number of transcribable Old Hispanic melodies by at least a factor of 100, and the number of complete notated Ambrosian office manuscripts exceeds the number of pitch-readable complete Old Hispanic office manuscripts (effectively zero) categorically (primary clause: the at-least-100x transcribable-melody ratio, Milan over Toledo; the verdict follows it). Original repertory size is treated as comparable a priori; coverage guard: the disparity is a survival-and-notation artifact of suppression, not of original scale, and the test voids only if the two rites' reconstructed original repertories differ by more than an order of magnitude.

Kill-dataset (verbatim)

Kill (partly built): the count of indexed pitch-readable Ambrosian office chants (the notated Ambrosian antiphoners, e.g. the Paleographie Musicale Ambrosian volumes, as indexed toward Cantus Index) against the register of transcribable Old Hispanic melodies; the operation is a ratio of readable-melody survivals between a continuous and a suppressed rite.

Novelty / leakage triage

already answered in the literature

Both registers are published and the survey literature already states the contrast as its own point: the Ambrosian office survives complete and pitch-readable across hundreds of notated manuscripts (Huglo's source census; Magistretti's Manuale; the Paleographie Musicale V-VI facsimile of BL Add. 34209; Bailey-Merkley's antiphon catalogue in the thousands, with responsories and psallendae on top), while the transcribable Old Hispanic register is the same 'about twenty' as the Leon item. A thousands-to-twenty ratio clears the 100x threshold by list-arithmetic on published catalogues, and Milan as the sole surviving non-Roman Latin chant rite - the control case against the suppressed rites - is the textbook framing itself.

• T. Bailey & P. Merkley, The Antiphons of the Ambrosian Office (Ottawa, 1989)
• M. Magistretti (ed.), Manuale Ambrosianum, 2 vols (Milan, 1904-1905)
• M. Huglo et al., Fonti e paleografia del canto ambrosiano (Milan, 1956)
• D.M. Randel, An Index to the Chant of the Mozarabic Rite (Princeton, 1973)

Predictions

No prediction registered yet.