arXiv:2606.26899cs.AI2026-06

让检索结果既符合目标属性又保持原始模式,解决传统方法的矛盾难题。

Generative Retrieval via Diffusion Transformer with Metric-Ordered Sequence Training and Hybrid-Policy Preference Optimization

论文配图:Generative Retrieval via Diffusion Transformer with Metric-Ordered Sequence Training and Hybrid-Policy Preference Optimization
图 1 · 摘自论文原文
  • 用扩散变换器生成查询向量,分阶段训练实现模式与属性双重优化。
  • 在四个属性领域中,交叉指标提升显著,七项测试中大幅领先。
  • 适合需要精准且一致推荐的应用,如个性化商品或内容推荐。

基于嵌入的检索通常通过向量相似度返回最高得分项,但在实际应用中常不满足需求:给定一个表达细粒度模式的种子集,需返回既满足目标属性又保持该模式的新项目。本文将此任务形式化为“模式保持属性检索”。两个目标相互冲突:平均种子能保留模式但落在低属性区域,而全局属性检索则会偏离原模式。为此提出连续生成式检索框架,模型读取项目嵌入序列并生成用于最近邻搜索的查询嵌入。提出MO-DiT+HPPO,包含原始序列预训练、多域度量有序延续预训练、尾部质心微调及混合策略偏好优化(HPPO)。度量有序训练将稀疏在线检索标签转化为从低到高预测属性密度的在模式轨迹,教会模型跨域的度量提升方向。HPPO通过在线交集度量标注混合候选池,并采用参考锚定偏好优化,对齐生成查询分布与真实在线目标。帕累托配对过滤器仅保留不降低同模式纯度的优对,提升属性指标而不牺牲模式一致性。在四项属性领域、项目与模式留出协议下,度量有序DiT优于预训练生成检索器,且HPPO进一步提升性能,在八组分割中的七组取得显著增益,最难分割仅小幅持平。度量预测验证、顺序消融、CPT/SFT对比及候选策略消融分析揭示了性能提升来源。

原文摘要 · Abstract (English)

Embedding-based retrieval ranks items by their similarity to a query in a shared vector space and usually aims to return the highest-scoring items. In many production settings this is not what is wanted: given a seed set that expresses a fine-grained pattern, one needs more items that both satisfy a target attribute and stay within that pattern. We formalize this as pattern-preserving attribute retrieval. The two goals pull against each other: averaging the seeds preserves the pattern but stays in a low-attribute region, while global attribute retrieval drifts to unrelated patterns. We approach the task with continuous generative retrieval, where a model reads a sequence of item embeddings and generates query embeddings for nearest-neighbor search. We propose MO-DiT+HPPO, a staged framework with raw-sequence pretraining, multi-domain metric-ordered continuation pretraining, tail-centroid fine-tuning, and HPPO. Metric-ordered training turns sparse online retrieval labels into in-pattern trajectories ordered from low to high predicted attribute density, teaching one model the metric-improvement direction across domains. HPPO aligns the generated query distribution with the true online objective by labeling a hybrid candidate pool with the online intersection metric and applying reference-anchored preference optimization. A Pareto pair filter keeps only winner pairs that do not lower same-pattern purity, raising the attribute metric without sacrificing the pattern. Across four attribute domains under item- and pattern-holdout protocols, metric-ordered DiT improves the intersection metric over a pretrained generative retriever, and HPPO improves it further, with significant gains on seven of eight domain-split cells and a marginal tie on the hardest split. Metric-predictor validation, order ablations, CPT/SFT comparisons, and a candidate-policy ablation show where the gains come from.

生成检索模式保持扩散模型偏好优化

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