| --- |
| license: apache-2.0 |
| task_categories: [text-generation] |
| tags: [dynamic-chunking, tokenization, hnet, boundaries, training-dynamics] |
| --- |
| |
| # H-Net chunker boundary probes |
|
|
| Longitudinal boundary decisions for 31 H-Net runs, logged on a **fixed, byte-identical** |
| FLORES+ probe at every checkpoint. This is the raw material for studying *when* a learned |
| segmentation stabilises. |
|
|
| ## Layout |
|
|
| `<run>/{step:06d}__{lang}.npz`, plus `<run>/probe_text.jsonl` (the raw probe text, so byte |
| offsets can be aligned to external gold data). |
|
|
| - **40 log-spaced steps**: 0, 1, 2, 4, 8, 16, 32, 64, 128, 200, then every 200 to 6000. |
| The early log-spacing is deliberate — uniform 200-step spacing misses the sharp early |
| transitions, and it cannot be recovered after a run. |
| - **12 languages**: de, el, en, fi, hi, my, ru, ta, th, tr, vi, zh |
| - 481 files per run (`jitter_*` runs have 157; they were logged at a coarser cadence). |
|
|
| ### npz keys |
|
|
| | key | shape | meaning | |
| |---|---|---| |
| | `mask` | `(L,) uint8` | 1 = a unit boundary falls before this byte | |
| | `score` | `(L,) float32` | the router's continuous boundary probability | |
| | `sent_offsets` | `(n_sent+1,) int64` | byte offset of each probe sentence | |
| | `bpb` | scalar | per-language bits-per-byte at this checkpoint | |
| | `step` | scalar | training step | |
| | `b_pad`, `p_pad`, `pad_mask` | `(128, 315)` | per-sentence padded views | |
|
|
| **Known issue:** `mask` and `mask_level1` (and `score`/`score_level1`) are byte-for-byte |
| identical — the two-level logging wrote the same level twice, so per-level word-vs-morph |
| typing cannot be done from these dumps. For Thai, `len(mask)` exceeds the probe byte length |
| by 21 bytes. Both are logging bugs, recorded here rather than silently patched. |
|
|
| ## Caveats worth knowing before you use these |
|
|
| - Boundaries are **phase-locked to a seed-arbitrary sub-character byte position**. Chunk |
| starts land on a UTF-8 character boundary 29–31% of the time against a 33% chance rate |
| (verified independently against the span dumps, not just the mask). |
| - 20 of 36 language-seed pairs have **not** converged by step 6000, so a step-6000 analysis |
| is measuring an unconverged segmentation for the low-resource half. |
| - Probe text decoded with `errors="ignore"` no longer byte-aligns to the mask for truncated |
| sentences (up to 35/128 for `my`); drop those rather than assume alignment. |
|
|
| Companion [models](https://huggingface.co/AdaptiveChunking/hnet-chunking-pilots) and |
| [results](https://huggingface.co/datasets/AdaptiveChunking/hnet-chunking-results). |
|
|
