| --- |
| license: other |
| license_name: sequential-hidden-decoding |
| license_link: LICENSE |
| base_model: |
| - Qwen/Qwen3-8B-Base |
| tags: |
| - sequential-hidden-decoding |
| - pretrained |
| - base-model |
| --- |
| |
| # Sequential-Hidden-Decoding-8B-n4 |
|
|
| This is the **n=4** variant of Sequential Hidden Decoding, a method that scales sequence length by n× with only additional Embedding parameters — same Transformer, more compute per token. |
|
|
| - **Base model:** [Qwen3-8B-Base](https://huggingface.co/Qwen/Qwen3-8B-Base) |
| - **Scale:** 4× |
| - **Additional Embedding Params:** 3.1B |
| - **Training Tokens:** 150B |
| - **Dtype:** bfloat16 |
|
|
| > **Note:** This is a **base model** (not instruction-tuned). It is intended for benchmarking, text completion, and as a foundation for downstream fine-tuning (SFT / RLHF). For conversational or instruction-following use cases, please fine-tune on your own data. |
|
|
| ## Key Idea |
|
|
| Prepare *n* independent Embedding matrices to encode the same token sequence *n* times, interleave the results, and feed the *n*×-length sequence into the same Transformer. Only the last embedding of each token computes the next-token loss, while the preceding embeddings serve as implicit reasoning steps in a continuous latent space. |
|
|
| ## Results |
|
|
| | Benchmark | # Shots | 8B Baseline | 8B scale n=2 | 8B scale n=4 | 8B scale n=8 | |
| |-----------|:-------:|:-----------:|:------------:|:------------:|:------------:| |
| | BBH (EM) | 3-shot | 78.8 | 81.3 | **83.0** | 83.9 | |
| | MMLU (EM) | 5-shot | 79.8 | 80.9 | **81.9** | 82.2 | |
| | MBPP+ (Pass@1) | 1-shot | 66.7 | 69.4 | **68.7** | 69.4 | |
| | MATH (LLM-judge) | 4-shot | 56.0 | 58.2 | **60.0** | 61.1 | |
| | ARC-C | 25-shot | 93.9 | 94.3 | **94.4** | 94.7 | |
| | Hellaswag | 10-shot | 79.7 | 83.1 | **85.0** | 85.3 | |
| | GSM8K | 4-shot | 92.5 | 93.3 | **93.9** | 94.6 | |
|
|
| ## Serving (SGLang) |
|
|
| This model requires a patched version of [SGLang](https://github.com/sgl-project/sglang) for inference. See the [project page](https://github.com/Tencent/Sequential-Hidden-Decoding) for installation options (Docker image, forked repo, or manual patch). |
|
|
| ```bash |
| python -m sglang.launch_server \ |
| --model-path tencent/Sequential-Hidden-Decoding-8B-n4 \ |
| --trust-remote-code \ |
| --tp-size 1 \ |
| --port 30000 --host 0.0.0.0 \ |
| --chunked-prefill-size -1 \ |
| --attention-backend fa3 \ |
| --mem-fraction-static 0.82 \ |
| --max-running-requests 32 \ |
| --context-length 131072 \ |
| --cuda-graph-max-bs 128 \ |
| --cuda-graph-bs 1 2 4 8 16 32 64 128 |
| ``` |
|
|
| ```python |
| from openai import OpenAI |
| |
| client = OpenAI(base_url="http://localhost:30000/v1", api_key="EMPTY") |
| response = client.completions.create( |
| model="tencent/Sequential-Hidden-Decoding-8B-n4", |
| prompt="The meaning of life is", |
| max_tokens=128, |
| temperature=0, |
| ) |
| print(response.choices[0].text) |
| ``` |
|
|
| ## All Models |
|
|
| | Model | Scale | Embedding Params | Training Tokens | |
| |-------|:-----:|:----------------:|:---------------:| |
| | [Sequential-Hidden-Decoding-8B-n2](https://huggingface.co/tencent/Sequential-Hidden-Decoding-8B-n2) | 2× | 1.9B | 75B | |
| | [Sequential-Hidden-Decoding-8B-n4](https://huggingface.co/tencent/Sequential-Hidden-Decoding-8B-n4) | 4× | 3.1B | 150B | |
| | [Sequential-Hidden-Decoding-8B-n8](https://huggingface.co/tencent/Sequential-Hidden-Decoding-8B-n8) | 8× | 5.6B | 187B | |
|
|
| ## Citation |
|
|
| ```bibtex |
| @article{hidden_decoding_2026, |
| title = {Hidden Decoding: Scaling Sequence Length in Pretraining}, |
| year = {2026}, |
| url = {https://welm.weixin.qq.com/posts/hidden_decoding/} |
| } |
| ``` |
|
|
| ## License |
|
|
| This model is released under the [License Terms of Sequential-Hidden-Decoding](LICENSE). |
|
|
