FableMogger9000/byzantine-synthetic-grammar

Byzantine Synthetic Interval-Grammar — Neume ↔ Western Pitch

A correct-by-construction supervised fine-tuning dataset for transcribing between Byzantine (Chrysanthine) neume notation and Western staff pitches, in both directions, over a diatonic interval grammar with ascending leaps up to an octave and rhythmic note durations.

This dataset trains the model `FableMogger9000/byzantine-synthetic-grammar-lora`, which reaches 96% exact-match / 98% melodic equivalence on the held-out neume→west direction.

Why "correct-by-construction"

Byzantine neumes are intervallic: each sign is a fixed degree-shift on the modal ladder. Instead of scanning manuscripts (whose neume and pitch streams are melismatic and do not align 1:1), each melody here is generated as a walk over those intervals — so the neume sequence and the pitch sequence are 1:1 aligned by a mathematical identity. There is nothing to recover and no labeling noise: the pairing is exact by definition.

Every row is re-derived by an independent verifier that does not import the generator (it re-declares its own interval table and re-computes each pitch), and only rows that pass are written.

Contents

• —Balanced across the four diatonic modes (Mode 1, pl. 1, 4, pl. 4) — ~25% each in both splits.
• —Zero leakage: the held-out split shares 0 exact input prompts with train (verified).
• —Deterministic gold: correctness is computable directly (no LLM judge); gold-vs-gold scores 100%.

Format

Chat-style JSONL. Each row:

{
  "id": "synth_000000_t0_n2w",
  "task": "neume_to_west",
  "synthetic": true,
  "messages": [
    {"role": "system", "content": "You are a Byzantine chant notation assistant. ..."},
    {"role": "user", "content": "Transcribe this Byzantine neume sequence (6 neumes) to Western staff pitches:\nMode 1\nIson: D4\noligon_hypsili ison oligon petaste apostrophos petaste"},
    {"role": "assistant", "content": "Mode 1\nIson: D4\nA4 A4 B4 C5 B4 C5"}
  ]
}

• —`task` is neume_to_west or west_to_neume.
• —The Ison line is the starting-pitch anchor — neume pitches are relative, so absolute pitch is only fixed once the ison is known. It is a reference, not the answer.
• —Held notes render inline as <pitch>:<beats> (e.g. C4:5).

Vocabulary (diatonic, degree-shift)

ison 0 · oligon/petaste +1 · apostrophos −1 · elaphron −2 · elaphron_apostrophos −3 · chamile −4 · oligon_kentema +3 · oligon_hypsili +4 · ypsili_left_oligon +5 · ypsili_kentima_oligon +6 · ypsili_over_kentima_oligon +7 (octave). Durations: apli (2 beats) · dipli (3) · tetrapli (5). Breath/barline signs are no-ops on pitch (neume→west only).

Scope and limitations

• —Diatonic only. Microtones, chromatic/enharmonic modes, fthora, and melisma are excluded by design — they cannot be faked deterministically and would break the correct-by-construction guarantee.
• —Not real manuscripts. This is synthetic grammar data, deliberately chosen because the available real neume↔pitch corpus does not correspond 1:1. It teaches the interval grammar, not real melismatic chant transcription.
• —west→neume is intrinsically ambiguous — multiple neumes encode the same pitch motion (e.g. oligon and petaste are both +1), so exact-match is capped in that direction; judge it by positional pitch accuracy.

Reproduce

Generated and checked by two scripts in the project repo:

python scripts/build_synthetic_musicality.py  --n 3000 --out data/byzantine/sft_synthetic_musicality.jsonl
python scripts/verify_synthetic_musicality.py data/byzantine/sft_synthetic_musicality.jsonl   # 0 errors

License

Apache-2.0.