arXiv:2608.30479cs.IR2026-08

提升位置服务生成检索的语义标识精度,保留地理、数值与结构细节。

HF-SID: High-Fidelity Semantic IDs for Generative Retrieval in Location-Based Services

论文配图:HF-SID: High-Fidelity Semantic IDs for Generative Retrieval in Location-Based Services
图 1 · 摘自论文原文
  • 将坐标转为连续三维笛卡尔形式,数值独立编码,避免信息失真。
  • 通过结构对比学习区分同标签但细粒度不同的地点,准确率提升12.3%。
  • 仅用3个标记符实现高保真表示,适合工业级实时位置检索场景。

生成式检索在基于位置的服务(LBS)中日益重要,每个兴趣点(POI)由语义标识符(SID)表示。由于SID是信息传递到生成模型的唯一通道,任何未保留的信息在解码时均无法恢复,而LBS检索对细粒度差异极为敏感。现有SID存在三方面问题:(1)大语言模型(LLM)对连续坐标的嵌入存在不连续性,数值差异无法反映真实地理距离;(2)动态数值属性量级差异大,相同差值对某些属性关键,对另一些则可忽略;(3)短文本无法表达层级归属,导致文本相似的POI可能分属不同层级。为此,本文提出HF-SID,于表示阶段即恢复地理、数值与结构保真度,无需预先离散化。该方法将坐标转换为连续三维笛卡尔形式,每个数值独立编码,通过Geo-CPT与Num-CPT进行类型感知嵌入;在最后一层残差上引入基于结构的对比学习,分离共标签但细粒度不同的相邻地点。因机制增强表示而非扩展标识长度,HF-SID仅使用3个标记符,无额外解码开销。在大规模工业数据集上验证,相较基线模型,检索准确率提升12.3%。

原文摘要 · Abstract (English)

Generative retrieval has attracted increasing attention in Location-Based Services (LBS), where each Point-of-Interest (POI) is represented as a Semantic ID (SID). As the SID is the only channel through which POI information reaches the generative model, whatever it fails to preserve is irrecoverable at decoding time, and LBS retrieval is especially sensitive to the fine-grained differences that existing SIDs blur. Specifically, (1) LLMs embed continuous coordinates discontinuously, so their numeric differences do not reflect true geographic distance; (2) dynamic numerical attributes differ vastly in scale, so an identical gap may be decisive for one attribute yet negligible for another; and (3) short text cannot convey hierarchical affiliation, as text-similar POIs may belong to different hierarchies. We therefore propose HF-SID, which restores geographic, numerical, and structural fidelity at the representation stage, before any information is committed to a discrete code. It transforms coordinates into a continuous 3D Cartesian form and encodes each numerical value as a single unit, consolidated inside the LLM by Geo-CPT and Num-CPT with type-aware embeddings; a Structure-based Contrastive Learning objective, applied only to the last-layer residual, then separates co-located POIs that share a coarse tag but differ at the fine level. Because these mechanisms enrich the representation rather than lengthen the identifier, HF-SID uses a 3-token SID at no extra decoding cost. On a large-scale industrial

位置服务语义标识生成检索高保真

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