BOND: Aligning LLMs with Best-of-N Distillation
<|reference_start|>BOND: Aligning LLMs with Best-of-N Distillation: Reinforcement learning from human feedback (RLHF) is a key driver of quality and safety in state-of-the-art large language models. Yet, a surprisingly simple and strong inference-time strategy is Best-of-N sampling that selects the best generation among N candidates. In this paper, we propose Best-of-N Distillation (BOND), a novel RLHF algorithm that seeks to emulate Best-of-N but without its significant computational overhead at inference time. Specifically, BOND is a distribution matching algorithm that forces the distribution of generations from the policy to get closer to the Best-of-N distribution. We use the Jeffreys divergence (a linear combination of forward and backward KL) to balance between mode-covering and mode-seeking behavior, and derive an iterative formulation that utilizes a moving anchor for efficiency. We demonstrate the effectiveness of our approach and several design choices through experiments on abstractive summarization and Gemma models. Aligning Gemma policies with BOND outperforms other RLHF algorithms by improving results on several benchmarks.<|reference_end|>
@article{sessa2024bond:,
    title={BOND: Aligning LLMs with Best-of-N Distillation},
    author={Pier Giuseppe Sessa, Robert Dadashi, L'eonard Hussenot, Johan Ferret,
  Nino Vieillard, Alexandre Ram'e, Bobak Shariari, Sarah Perrin, Abe Friesen,
  Geoffrey Cideron, Sertan Girgin, Piotr Stanczyk, Andrea Michi, Danila
  Sinopalnikov, Sabela Ramos, Am'elie H'eliou, Aliaksei Severyn, Matt
  Hoffman, Nikola Momchev, Olivier Bachem},
    journal={arXiv preprint arXiv:2407.14622},
    year={2024},
    archivePrefix={arXiv},
    eprint={2407.14622},
    primaryClass={cs.LG cs.AI cs.CL}
}