发表机构
New York University; Fudan University（纽约大学; 复旦大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对时间变形下序列检索不稳定问题，提出固定支架编码器GeoPatch，将几何仅作条件变量，保持令牌支持不变，提升早期排名检索性能。
AI 中文摘要
基于嵌入的检索对于长序列集合具有吸引力，因为每个项目可以被编码一次，并通过最近邻排序进行搜索。困难在于被索引的对象通常是在非标准时钟下观测的：心脏周期随心率拉伸，语音随节奏变化，传感器轨迹在不同速度下达到相似状态。本文研究了在这种情境下基于补丁的编码器中一个特定的不稳定性来源。如果补丁边界由信号几何决定，那么分词可能会在表示预期容忍的相同时间变形下发生变化。我们提出了GeoPatch，一种固定支架补丁编码器，它使令牌支持独立于几何，并仅将斜率、曲率、加速度、仿射残差和置信度描述符用作连续条件变量。该设计将边界变化转化为特征调制：几何可以通过受控路径改变嵌入，但不能改变局部令牌的数量、顺序或支持。我们通过机制级稳定性分析来形式化这一区别，该分析区分了边界漂移、仿射时间变化、置信度加权的几何扰动和检索边际效应。相同的局部令牌支持全局嵌入检索和后期交互评分，因此评分规则可以与评估协议匹配。在ECG、语音和多变量时间序列检索任务中，GeoPatch在时间变化下改善了早期排名检索，同时揭示了局部表面匹配和严格非重叠检索之间的明确权衡。
英文摘要
Embedding-based retrieval is attractive for long sequence collections because each item can be encoded once and searched by nearest-neighbor ranking. The difficulty is that the objects being indexed are often observed under a noncanonical clock: cardiac cycles stretch with rate, speech changes with tempo, and sensor traces reach comparable states at different speeds. This paper studies a specific source of instability in patch-based encoders for this regime. If patch boundaries are chosen from signal geometry, then the tokenization can change under the same temporal deformation that the representation is expected to tolerate. We propose GeoPatch, a fixed-scaffold patch encoder that keeps token support independent of geometry and uses slope, curvature, acceleration, affine-residual, and confidence descriptors only as continuous conditioning variables. The design turns boundary variation into feature modulation: geometry can change the embedding through a controlled pathway, but it cannot change the number, order, or support of local tokens. We formalize this distinction through a mechanism-level stability analysis that separates boundary drift, affine timing variation, confidence-weighted geometry perturbation, and retrieval-margin effects. The same local tokens support global embedding retrieval and late-interaction scoring, so the scoring rule can be matched to the evaluation protocol. Across ECG, speech, and multivariate time-series retrieval tasks, GeoPatch improves early-rank retrieval under timing variation while exposing a clear trade-off between local surface matching and strict non-overlap retrieval.
