Session 8: Phase 4: the chancery key; book v1.3

Date: 2026-10-22

• Survey: fifteenth-century Italian mixed keys and the methods used to break them (Meister 1906, Pelling on the Tranchedino ledger, Costamagna 1977, Simonetta 1474, Megyesi et al. 2021/2022, Lasry 2024 on syllabic ciphers, Kopal 2019, Oranchak et al. on the Zodiac, Aldarrab & May on unit segmentation): REPORT_mixed_keys.md, with simulator parameter ranges.
• Registry: H-CIPHER-MIXED added with four predictions before any test; frozen copy out/hypotheses_preregistered_partVII.yaml (sha256 803e2097...).
• Simulator (mixedkey.py): letters with homophones, syllable signs, nomenclator, nulls; signs drawn from the manuscript's own slot strings by position; three spacing practices; plaintext Latin of the manuscript's genres by section. Option unique_signs added after the solver diagnostic showed that position tables could share a string between two readings.
• T19 family map: 216 keys (out/mixed_grid_*.csv). No key within 2 of the manuscript's locality (max 10.2, bounded by the plaintext's 10.3); word spacing keeps locality and order and makes words of 8.5-13 glyphs; split words give spelling-use coupling and edge dependency but the previous word always helps; stream hides order and loses locality. Line-initial effect ~0.001 everywhere (manuscript 0.198). Fitted keys, 20 corpora each: fail 12, 10 and 9 of 12 held-out statistics (out/mixed_scores.csv). P1 fails.
• T20 collapse: the registered word-merge was degenerate (chaining); revised to sign-level alternations at matched vocabulary (t_collapse3.py). Manuscript: context merges give ~3x the repeated 4-grams of random merges at equal vocabulary, but word order does not return; Latin shows part of the same effect (built into the measure); the simulated keys give too few single-glyph alternations for the test to see them. P2 not supported; instrument underpowered.
• T21 choice dynamics: manuscript 1.04 (scribes 1.02-1.08); the measure cannot separate random, cycling and sticky choice on the simulated keys. P3 untestable with this instrument.
• T21c (new, not registered): variant choice within minimal-pair frames vs line position, paragraph-first/last lines excluded, 500 within-page shuffles. Manuscript: 6 of 10 alternations at z 3.9-9.2 (both Currier languages); Latin in the same lines 0/10; simulated keys 1/33 (z 3.4); Vulgate one verse per line, enciphered: 0/10. The spelling was chosen with the line in view, after any encipherment.
• T23 (exploratory): Simonetta's 1474 rules. Eight word-final glyphs above 1%, top five 91% (Italian 11 / 83%, Latin 12 / 71%): endings more concentrated than plain Italian, the opposite of vowel homophones; q followed by o 97.6%.
• T22 solver. Two character-level objectives failed (salad, 0-16% of planted key). Element-vocabulary annealing after Lasry 2024 (elem_solver.py): letters, syllables, nomenclator words, space and null as elements; element trigram LM on the reference decomposed the same way; KL frequency penalty; incremental KL (same results, ~20x faster). Ladder with unique signs: L1 98% key / 89% words; L2 97/86; L3 95/81; L4 86/53 (pass). L5 (signs unknown): lexicon segmentation 6%; unigram unit discovery (useg.py; boundary F1 0.88, 76-83% of sign tokens exact) 25% key, 9% words; L6 20%. Diagnostic: from the best key the learned segmentation allows, the joint loop degrades the segmentation (82% -> 60% exact) - a model failure, not search. By the registered rule the hypothesis is untested beyond L4.
• T22b manuscript (exploratory given the L5 failure): held-out element score real vs spelling-permuted null - control (L5-type) gap 0.60; manuscript Latin 0.27, Italian 0.44; stream: control fails (real below null). Dictionary coverage does not separate real from permuted even for the control (0.33 vs 0.36). Content-free comparisons (slot grammar, self-copying) and a second seed: see out/elem_voynich.csv.
• Book: Part VII (ch. 28 Chancery Keys, ch. 29 Looking for the Key), closing chapter moved to the end and revised; three figures (family map, line position, ladder), table 28.1; Appendix E regenerated, Appendix F extended.
• Open: the layout layer (model and normalise line-conditioned variants, then re-run); a copying layer; a solver that can find glyph-string signs (slot-constrained segmentation, lattice decoding with a neural LM); a more topical plaintext for the locality bound.