---
pretty_name: Stage 3 Final Mixture — 50% CoT Compression
license: apache-2.0
task_categories:
- text-generation
---

# Stage 3 Final Mixture — 50% CoT Compression

This is a deterministic capability-preserving rewrite of
`leonli66/stage3-final-mixture` for LCLM Stage-3 post-training.

Only the `reasoning_data` and `dolci_think` subsets change. Their
`compression_prompt` is the ordinary `prompt`. A deterministic 50% arm keeps
the complete assistant target as ordinary SFT; the other arm wraps the inferred
reasoning prefix in `<|memory_start|>...<|memory_end|>` while keeping the final
answer trainable. All non-reasoning rows are unchanged.

## Counts

- Total rows: 20,326,114
- Reasoning rows: 5,407,421
- Assigned CoT compression: 2,702,448 (49.98%)
- Assigned ordinary uncompressed SFT: 2,704,973 (50.02%)
- Effective CoT-compressed rows: 2,698,545
- Compression-assigned rows too short to split: 3,903

## Boundary rules

Priority is: explicit analysis tags; final-answer markers; a final boxed answer;
an answer line; the final balanced fenced block; a GSM-style final `####` line;
then a fallback that keeps the final 128
`Qwen/Qwen3-4B-Instruct-2507` tokens uncompressed.

The transformation is text-preserving: deleting the two LCLM memory tags from
every rewritten target reconstructs the original target exactly. All 2,033
Parquet shards were validated against the source.