arXiv:2511.18891cs.CL2025-11被引 1

用开源大模型复现语言模型贝叶斯优化,验证其有效性与鲁棒性。

Reproducibility Study of Large Language Model Bayesian Optimization

  • 以Llama 3.1 70B替代GPT-3.5,保持文本交互方式复现原方法。
  • 文本上下文显著降低早期损失且减少实验波动,提升建议多样性。
  • 小模型无法稳定工作,说明大模型容量对代理性能至关重要。

本可复现研究重新审视Daxberger等(2024)提出的LLAMBO框架,该方法通过纯文本交互,利用大语言模型作为判别性代理和获取函数优化器进行贝叶斯优化。我们在原始评估协议下复现了核心的Bayesmark和HPOBench实验,但将GPT-3.5替换为开放权重的Llama 3.1 70B模型,用于所有文本编码组件。结果基本验证了LLAMBO的主要结论:通过文本形式的问题和超参数描述进行上下文预热,显著改善早期遗憾表现并降低运行间的方差。尽管LLAMBO的判别性代理在单任务回归上弱于高斯过程(GP)或SMAC,但受益于语言模型带来的跨任务语义先验。移除文本上下文会明显降低预测准确性和校准性,而LLAMBO候选采样器始终生成质量更高、更多样化的建议,优于TPE或随机采样。使用较小模型(Gemma 27B、Llama 3.1 8B)时出现不稳定或无效预测,表明其缺乏可靠代理行为所需的能力。总体而言,本研究证明LLAMBO架构对语言模型骨干的更换具有鲁棒性,在采用Llama 3.1 70B时仍保持有效性。

原文摘要 · Abstract (English)

In this reproducibility study, we revisit the LLAMBO framework of Daxberger et al. (2024), a prompting-based Bayesian optimization (BO) method that uses large language models as discriminative surrogates and acquisition optimizers via text-only interactions. We replicate the core Bayesmark and HPOBench experiments under the original evaluation protocol, but replace GPT-3.5 with the open-weight Llama 3.1 70B model used for all text encoding components. Our results broadly confirm the main claims of LLAMBO. Contextual warm starting via textual problem and hyperparameter descriptions substantially improves early regret behaviour and reduces variance across runs. LLAMBO's discriminative surrogate is weaker than GP or SMAC as a pure single task regressor, yet benefits from cross task semantic priors induced by the language model. Ablations that remove textual context markedly degrade predictive accuracy and calibration, while the LLAMBO candidate sampler consistently generates higher quality and more diverse proposals than TPE or random sampling. Experiments with smaller backbones (Gemma 27B, Llama 3.1 8B) yield unstable or invalid predictions, suggesting insufficient capacity for reliable surrogate behaviour. Overall, our study shows that the LLAMBO architecture is robust to changing the language model backbone and remains effective when instantiated with Llama 3.1 70B.

贝叶斯优化大模型可复现性超参调优

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