SimpleSD-4B-thinking

This model is an example of the Simple Self-Distillation (SimpleSD) method that improves code generation by fine-tuning a language model on its own sampled outputs—without rewards, verifiers, teacher models, or reinforcement learning. Please see the paper below for more information. This uses Qwen for initialization.

Self-distillation sampling: temperature=1.1, top_p=0.95, top_k=20
Evaluation sampling: temperature=0.7, top_p=0.95, top_k=20

paper: https://arxiv.org/abs/2604.01193

code: https://github.com/apple/ml-ssd

Notes

These are research checkpoints for reproducibility.
They are not optimized Qwen releases.
They don't represent a broader open-source model strategy.

Usage

from transformers import AutoModelForCausalLM, AutoTokenizer

model = AutoModelForCausalLM.from_pretrained("apple/SimpleSD-4B-thinking")
tokenizer = AutoTokenizer.from_pretrained("apple/SimpleSD-4B-thinking")

Method

SimpleSD samples solutions from the base model using non-unit temperature and top-k/top-p truncation, then fine-tunes on those samples via standard supervised learning. Despite its simplicity, SimpleSD yields large gains on competitive programming benchmarks, with improvements concentrating on harder problems. The mechanism traces to resolving a precision–exploration conflict: SimpleSD reshapes token distributions in a context-dependent way so that a single global decoding configuration becomes far more effective at evaluation time.

Results

LiveCodeBench (%)

Model	LCBv6 pass@1	LCBv6 pass@5	LCBv5 pass@1	LCBv5 pass@5
Qwen3-4B-Thinking-2507 (base)	54.5	67.5	59.6	70.3
+ SimpleSD (this model)	57.8 (+3.3)	71.4 (+3.9)	63.1 (+3.5)	74.7 (+4.4)

Paper

Embarrassingly Simple Self-Distillation Improves Code Generation

@misc{zhang2026embarrassinglysimpleselfdistillationimproves,
      title={Embarrassingly Simple Self-Distillation Improves Code Generation},
      author={Ruixiang Zhang and Richard He Bai and Huangjie Zheng and Navdeep Jaitly and Ronan Collobert and Yizhe Zhang},
      year={2026},
      eprint={2604.01193},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2604.01193},
}