arXiv:2504.05321cs.IRcs.AI2025-04KDD被引 5

让大模型生成更值钱的搜索关键词,直接结合实时商业价值。

VALUE: Value-Aware Large Language Model for Query Rewriting via Weighted Trie in Sponsored Search

  • 用加权字典树存储关键词实时价值,生成时动态调整概率。
  • 在离线测试中,语义和商业价值指标均显著优于基线方法。
  • 已部署于双十一大促系统,能快速响应价值波动,适合广告推荐场景。

查询到竞价关键词(bidword)的重写是赞助搜索的核心任务,将用户噪声查询转化为语义相关且具有商业价值的关键词。尽管大语言模型(LLM)通过生成式检索提升了语义相关性,但通常忽略关键词的商业价值,导致重写结果语义正确却经济收益不佳,需额外引入基于人类反馈的强化学习(RLHF)阶段进行优化。然而传统偏好对齐易过度强调关键词排序,且易过拟合,降低重写质量。此外,关键词价值变化迅速,现有生成方法难以及时响应。为此,我们提出VALUE(Value-Aware Large Language Model for Query Rewriting via Weighted Trie),将价值感知直接融入生成过程,并在训练中增强价值对齐。该框架采用加权字典树(Weighted Trie)这一新型结构,为每个词元存储实时价值信号。解码过程中,利用这些信号调整模型词元概率,限制搜索空间,引导生成高价值重写结果。对齐阶段采用细粒度偏好学习策略,强调稳定、高价值差异,弱化噪声或瞬时波动,提升鲁棒性并减少过拟合。离线实验表明,VALUE在语义匹配与价值导向指标上显著优于基线。自2024年10月起,VALUE已部署于我方广告系统,并成功支撑中国最大购物节“双十一大促”。

原文摘要 · Abstract (English)

Query-to-bidword(i.e., bidding keyword) rewriting is fundamental to sponsored search, transforming noisy user queries into semantically relevant and commercially valuable keywords. Recent advances in large language models (LLMs) improve semantic relevance through generative retrieval frameworks, but they rarely encode the commercial value of keywords. As a result, rewrites are often semantically correct yet economically suboptimal, and a reinforcement learning from human feedback (RLHF) stage is usually added after supervised fine-tuning(SFT) to mitigate this deficiency. However, conventional preference alignment frequently overemphasize the ordering of bidword values and is susceptible to overfitting, which degrades rewrite quality. In addition, bidword value changes rapidly, while existing generative methods do not respond to these fluctuations. To address this shortcoming, we introduce VALUE(Value-Aware Large language model for qUery rewriting via wEighted trie), a framework that integrates value awareness directly into generation and enhances value alignment during training. VALUE employs the Weighted Trie, a novel variant of the classical trie that stores real-time value signals for each token. During decoding, the framework adjusts the LLM's token probabilities with these signals, constraining the search space and steering generation toward high-value rewrites. The alignment stage uses a fine-grained preference learning strategy that emphasizes stable, high-value differences and down-weights noisy or transient fluctuations, thereby improving robustness and reducing overfitting. Offline experiments show that VALUE significantly outperforms baselines in both semantic matching and value-centric metrics. VALUE has been deployed on our advertising system since October 2024 and served the Double Eleven promotions, the biggest shopping carnival in China.

搜索广告大模型价值感知关键词生成

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