arXiv:2607.26418cs.IR2026-07

提出并行重排序框架DIRECTOR,解决推荐系统中候选集选择与排序的效率与质量矛盾。

DIRECTOR: Dynamic Index-based Recommendation with Transport-Optimized Retrieval

论文配图:DIRECTOR: Dynamic Index-based Recommendation with Transport-Optimized Retrieval
图 1 · 摘自论文原文
  • 通过动态索引和运输优化,在并行中实现全局结构协调
  • 训练时用熵正则化运筹学监督,推理时直接硬匹配生成无重复结果
  • 适合大规模工业推荐场景,对复杂评估器兼容性强

重排序是组合决策问题,旨在从请求相关的候选集中选出并排列高价值推荐列表。现有自回归模型逐位生成,受贪婪或有限宽度解码限制,易提前剪枝全局最优排列且存在固有串行延迟。非自回归方法虽支持并行预测,但各位置独立处理导致跨位置协调不足,可能产生重复或冲突项。为此,我们提出基于动态索引的推荐框架DIRECTOR,将候选项映射到连续潜在空间,平行生成所有目标位置的请求相关检索索引。训练阶段采用熵正则化运筹学提供冲突感知监督;推理阶段直接在相似度矩阵上进行全局硬匹配,无需迭代运输即可生成无重复列表。为使生成器适配仅返回标量效用的隐式评估器,引入前缀锚定信用分配机制,将全局奖励转化为位置级训练信号。大量离线与在线实验表明,DIRECTOR持续优于强基线,在大规模工业推荐场景中取得显著提升。

原文摘要 · Abstract (English)

Reranking is a combinatorial decision problem that aims to select and order a high-utility slate from a request-specific candidate set. A major line of generative rerankers adopts autoregressive (AR) models, which construct the slate one position at a time to capture inter-position dependencies. However, under practical greedy or bounded-width decoding, prefix-based search may prematurely prune globally promising permutations and incurs inherently sequential latency, restricting the effective search space under a fixed serving budget. Non-autoregressive (NAR) alternatives alleviate this efficiency bottleneck through position-parallel prediction, but naive position-wise factorization treats different positions too independently, leading to insufficient cross-position coordination and potentially duplicate or conflicting item selections. To retain parallel efficiency while introducing global structural coordination, we propose Dynamic Index-based RECommendation with Transport-Optimized Retrieval (DIRECTOR), a transport-guided parallel reranking framework. DIRECTOR maps candidate items into a continuous latent space and generates request-conditioned dynamic retrieval indices for all target positions in parallel. During training, it uses entropy-regularized OT to provide conflict-aware supervision; at inference, it directly performs global hard matching on similarity matrix, producing duplicate-free slates without iterative transport. To further align the generator with an opaque list-wise evaluator that returns only a scalar utility, we introduce a prefix-anchored credit assignment mechanism that converts the global reward into position-specific training signals. Extensive offline and online experiments demonstrate that DIRECTOR consistently outperforms strong reranking baselines, achieving significant improvement in large-scale industrial recommendation scenarios.

推荐系统并行重排序运输优化

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