---
language:
- en
license: apache-2.0
base_model: Qwen/Qwen3-1.7B
tags:
- qthink
- continuous-thought
- latent-reasoning
- distillation
- gsm8k
datasets:
- openai/gsm8k
metrics:
- accuracy
model-index:
- name: r11_uniform_perstep_g2_ans256
  results:
  - task:
      type: math-reasoning
      name: Grade School Math
    dataset:
      name: GSM8k
      type: openai/gsm8k
      split: test
    metrics:
    - type: accuracy
      value: 83.2
      name: Accuracy
---

# r11_uniform_perstep_g2_ans256

**Best overall — uniform multi-rollout per-step distillation (83.2%)**

- **Best result across all experiments**: 83.2% on GSM8k
- Uses uniform teacher (average over ALL 16 rollouts, including incorrect)
- Per-step distillation at every latent step with γ=2.0
- Trained with max_answer_len=256

## Overview

This model implements **QThink** (Parallel Latent Reasoning via Per-Step Distillation of
Multiple Rollouts) — an autoregressive latent reasoning loop that processes K=6 continuous
thought steps before generating a text answer. Teacher hidden states are extracted from
multiple chain-of-thought rollouts generated by the base model and distilled into the latent
representations at every step.

**Key idea**: Instead of distilling from a single reasoning trace, we aggregate hidden states
from multiple rollouts (16 per problem) and supervise every latent step. The teacher signal
is the uniform average of ALL rollouts (correct + incorrect).

## Architecture

- **Base model**: Qwen3-1.7B (1.7B parameters)
- **Fine-tuning**: LoRA (rank=32, alpha=16) on q/k/v/o/gate/up/down_proj
- **Projection head**: Linear(2048, 2048) → GELU → Linear(2048, 2048) → LayerNorm(2048)
- **Latent steps**: K=6 autoregressive continuous thought steps
- **Inference**: Process prompt → K latent steps via ProjectionHead + KV cache → greedy text generation

## Training Details

| Parameter | Value |
|---|---|
| Mode | `codi_uniform` |
| Per-step distillation | `True` |
| Distillation γ | 2.0 |
| Learning rate | 0.0002 |
| Epochs | 3 |
| Batch size (per GPU) | 1 |
| Gradient accumulation | 16 |
| Effective batch size | 128 (across 8 GPUs) |
| Max answer length | 256 |
| Latent steps (K) | 6 |
| Task | GSM8k (7,473 training problems) |
| Rollouts per problem | 16 |
| **GSM8k test accuracy** | **83.2%** |

## How to Use

### Requirements

```bash
pip install torch transformers
```

### Inference Code

```python
import torch
import torch.nn as nn
from transformers import AutoModelForCausalLM, AutoTokenizer

# Load model
model_name = "LakshyAAAgrawal/continuous-thought-r11_uniform_perstep_g2_ans256"
tokenizer = AutoTokenizer.from_pretrained(model_name)
model = AutoModelForCausalLM.from_pretrained(
    model_name, torch_dtype=torch.bfloat16, device_map="auto"
)
model.eval()

# Load projection head
class ProjectionHead(nn.Module):
    def __init__(self, hidden_size):
        super().__init__()
        self.mlp = nn.Sequential(
            nn.Linear(hidden_size, hidden_size),
            nn.GELU(),
            nn.Linear(hidden_size, hidden_size),
            nn.LayerNorm(hidden_size),
        )
    def forward(self, x):
        return self.mlp(x)

proj = ProjectionHead(model.config.hidden_size)
proj.load_state_dict(torch.load(
    hf_hub_download(model_name, "projection_head.pt"), map_location="cpu"
))
proj = proj.to(model.dtype).to(model.device).eval()

# Generate with latent reasoning
question = "Natalia sold clips to 48 of her friends in April, and then she sold half as many clips in May. How many clips did Natalia sell altogether in April and May?"
messages = [{"role": "user", "content": f"Solve the following math problem step by step. Show your work and put your final numerical answer after ####.\n\n{question}"}]
prompt = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
inputs = tokenizer(prompt, return_tensors="pt").to(model.device)

# Step 1: Process prompt
with torch.no_grad():
    out = model(**inputs, output_hidden_states=True, use_cache=True)
    past_kv = out.past_key_values
    latent = out.hidden_states[-1][:, -1, :]  # last token hidden state

    # Step 2: K latent reasoning steps
    mask = inputs["attention_mask"].clone()
    for k in range(6):
        latent = proj(latent)
        mask = torch.cat([mask, torch.ones(1, 1, device=mask.device, dtype=mask.dtype)], dim=1)
        out = model(inputs_embeds=latent.unsqueeze(1), attention_mask=mask,
                    past_key_values=past_kv, output_hidden_states=True, use_cache=True)
        past_kv = out.past_key_values
        latent = out.hidden_states[-1][:, -1, :]

    # Step 3: Greedy text generation
    next_token = out.logits[:, -1, :].argmax(dim=-1)
    generated = [next_token]
    for _ in range(2047):
        if next_token.item() == tokenizer.eos_token_id:
            break
        mask = torch.cat([mask, torch.ones(1, 1, device=mask.device, dtype=mask.dtype)], dim=1)
        out = model(input_ids=next_token.unsqueeze(0), attention_mask=mask,
                    past_key_values=past_kv, use_cache=True)
        past_kv = out.past_key_values
        next_token = out.logits[:, -1, :].argmax(dim=-1)
        generated.append(next_token)

    response = tokenizer.decode(torch.cat(generated), skip_special_tokens=True)
    print(response)
```

### Evaluation

To evaluate on the full GSM8k test set, use the evaluation script from our repository:

```bash
python evaluate.py \
    --model_dir LakshyAAAgrawal/continuous-thought-r11_uniform_perstep_g2_ans256 \
    --mode codi_uniform \
    --output results/r11_uniform_perstep_g2_ans256.json \
    --max_new_tokens 2048 \
    --num_latent 6
```

**Important**: Use `max_new_tokens=2048` for evaluation. The model generates verbose
chain-of-thought text after the latent steps, requiring more tokens than standard models.

## Results Comparison

| Model | Mode | Per-step | γ | ans_len | GSM8k Accuracy |
|---|---|---|---|---|---|
| **This model** | **codi_uniform** | **True** | **2.0** | **256** | **83.2%** |
| Qwen3-1.7B (base) | — | — | — | — | 77.3% |
| Discrete SFT | sft | — | — | — | 80.7% |
| QThink RW final-step | rw | no | 1.0 | 128 | 81.0% |
| QThink Uniform per-step ans256 | uniform | yes | 2.0 | 256 | 83.2% |
| QThink RW per-step ans256 | rw | yes | 1.0 | 256 | 82.7% |

## Citation

If you use this model, please cite:

```bibtex
@misc{continuous-thought-2025,
  title={QThink: Parallel Latent Reasoning via Per-Step Distillation of Multiple Rollouts},
  author={Lakshya Agrawal},
  year={2025},
  url={https://huggingface.co/LakshyAAAgrawal/continuous-thought-r11_uniform_perstep_g2_ans256}
}
```