---
pretty_name: omissionweb-cm
language: [en]
license: cc-by-nc-4.0
task_categories: [text-generation]
tags: [interpretability, activation-verbalization, omission, paraphrase, synthetic]
---

# omissionweb-cm — severity-graded omission corpus from ClimbMix

**98,137 rows** (96,137 train / 2,000 test, test held out by source document). Each row pairs a short web SPAN with an ABRIDGED rewrite that omits **exactly one fact** at a sampled severity, plus that fact as a standalone gold sentence.

Built as *percept-free* warmstart data for natural-language-activation research: an auditor model learns to verbalize what a subject model's activations contain beyond an abridged context, where the gold is an objectively omitted fact — model-independent, with zero percept/impression supervision. Successor to the FineWeb-based omissionweb v1/v2: higher source quality (ClimbMix), frontier-model abridging (claude-sonnet-5 instead of a 35B), an explicit abridging-severity knob, and natural sentence-final punctuation (no punctuation-type filtering).

## Schema

| field | meaning |
|---|---|
| `sentence` | the source span (1–2 sentences, 8–45 words; what the subject model reads) |
| `abridged` | fluent rewrite omitting exactly ONE fact; the remainder must not imply the omitted fact |
| `percept` | the omitted fact as one standalone sentence (gold; anchor entity named, ≤22 words, median 10) |
| `type` | `sev1`–`sev4`, the abridging severity (see below) |
| `doc_idx` | source provenance `s{shard}r{row}` in `nvidia/ClimbMix` `climbmix_small` |
| `split` | `train` / `test` (2,000 test rows, held out by document) |

Severity distribution: sev1 14,648 · sev2 29,626 · sev3 34,618 · sev4 19,245.

## Severity levels

- **1**: light paraphrase; drop one peripheral detail.
- **2**: clear paraphrase throughout; drop one distinct fact.
- **3**: aggressive rewording and compression; drop one load-bearing fact.
- **4**: compress to a one-sentence gist; drop the most specific fact.

## Generating prompt

One request covers 6 spans (claude-sonnet-5, Message Batches, thinking disabled, max_tokens 1400):

```
For each numbered SPAN below, write an ABRIDGED rewrite and the OMISSION, at the given severity.

Rules:
- ABRIDGED: a fluent rewrite that omits exactly ONE fact from the span. Reword throughout — never
  copy a clause word-for-word. The remaining content must NOT imply, entail, or hint at the omitted
  fact: a reader of ABRIDGED alone must have no way to recover it (watch out for synonyms and
  consequences that leak it). Invent nothing.
- OMISSION: the omitted fact as ONE standalone sentence, at most 22 words, naming its anchor entity
  explicitly (no bare pronouns). State the fact itself; writing about the text ("the passage
  mentions...") is banned.
- SEVERITY 1: light paraphrase; drop one peripheral detail.
- SEVERITY 2: clear paraphrase throughout; drop one distinct fact.
- SEVERITY 3: aggressive rewording and compression; drop one load-bearing fact.
- SEVERITY 4: compress to a one-sentence gist; drop the most specific fact.
- If a span is incoherent junk (navigation boilerplate, raw lists, gibberish), OR too thin to remove
  one whole fact while leaving substantive content (never resort to adjective-level omissions like
  "the marks were precise"), return {"i": N, "skip": true} for it.

Return EXACTLY one JSON object per line, one per span, no other text:
{"i": 1, "abridged": "...", "omission": "..."}

SPAN 1 (severity 3): ...
```

## Pipeline (`pipeline/omissionweb_cm.py`, stages `spans | smoke | submit | collect`)

1. **Spans**: `nvidia/ClimbMix` `climbmix_small/shard_0` (GPT-2-tokenized), detokenized; per document one random newline-segment is sentence-split and a 1–2-sentence window sampled. Filters: 8–45 words, sentence-initial capital (no mid-sentence fragments), natural sentence-final punctuation, no trailing ellipsis, instruction/code-marker ban (`input:`, code fences, HTML, URLs), ≥97% ASCII letters (non-English screen), ≥2 common stopwords, digit/symbol/repetition caps. 102,000 spans with severities sampled at 15/30/35/20%.
2. **Generation**: 17,000 batch requests → the model returned `skip` for 3,645 junk/thin spans; 218 rows (0.21%) dropped as malformed.
3. **Assembly**: structural validation, by-document test holdout.

## Caveats

- Source is quality-filtered web text (ads/edu-value classifiers per the CLIMB paper) but still web: instructional/product/forum registers are represented.
- Leak control (abridged must not entail the omission) is prompt-level; no post-hoc entailment audit has been run yet.
- License **CC BY-NC 4.0** inherited from ClimbMix; research use only.

![stats](omissionweb_cm_stats.png)