LLMs as Sparse Retrievers:A Framework for First-Stage Product Search

Fuente: arXiv
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Autori principali: Song, Hongru, Liu, Yu-an, Zhang, Ruqing, Guo, Jiafeng, de Rijke, Maarten, Li, Sen, Peng, Wenjun, Lv, Fuyu, Cheng, Xueqi
Natura: Preprint
Pubblicazione: 2025
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author Song, Hongru
Liu, Yu-an
Zhang, Ruqing
Guo, Jiafeng
de Rijke, Maarten
Li, Sen
Peng, Wenjun
Lv, Fuyu
Cheng, Xueqi
author_facet Song, Hongru
Liu, Yu-an
Zhang, Ruqing
Guo, Jiafeng
de Rijke, Maarten
Li, Sen
Peng, Wenjun
Lv, Fuyu
Cheng, Xueqi
contents Product search is a crucial component of modern e-commerce platforms, with billions of user queries every day. In product search systems, first-stage retrieval should achieve high recall while ensuring efficient online deployment. Sparse retrieval is particularly attractive in this context due to its interpretability and storage efficiency. However, sparse retrieval methods suffer from severe vocabulary mismatch issues, leading to suboptimal performance in product search scenarios. With their potential for semantic analysis, large language models (LLMs) offer a promising avenue for mitigating vocabulary mismatch issues and thereby improving retrieval quality. Directly applying LLMs to sparse retrieval in product search exposes two key challenges:(1)Queries and product titles are typically short and highly susceptible to LLM-induced hallucinations, such as generating irrelevant expansion terms or underweighting critical literal terms like brand names and model numbers;(2)The large vocabulary space of LLMs leads to difficulty in initializing training effectively, making it challenging to learn meaningful sparse representations in such ultra-high-dimensional spaces.To address these challenges, we propose PROSPER, a framework for PROduct search leveraging LLMs as SParsE Retrievers. PROSPER incorporates: (1)A literal residual network that alleviates hallucination in lexical expansion by reinforcing underweighted literal terms through a residual compensation mechanism; and (2)A lexical focusing window that facilitates effective training initialization via a coarse-to-fine sparsification strategy.Extensive offline and online experiments show that PROSPER significantly outperforms sparse baselines and achieves recall performance comparable to advanced dense retrievers, while also achieving revenue increments online.
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id arxiv_https___arxiv_org_abs_2510_18527
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle LLMs as Sparse Retrievers:A Framework for First-Stage Product Search
Song, Hongru
Liu, Yu-an
Zhang, Ruqing
Guo, Jiafeng
de Rijke, Maarten
Li, Sen
Peng, Wenjun
Lv, Fuyu
Cheng, Xueqi
Information Retrieval
Product search is a crucial component of modern e-commerce platforms, with billions of user queries every day. In product search systems, first-stage retrieval should achieve high recall while ensuring efficient online deployment. Sparse retrieval is particularly attractive in this context due to its interpretability and storage efficiency. However, sparse retrieval methods suffer from severe vocabulary mismatch issues, leading to suboptimal performance in product search scenarios. With their potential for semantic analysis, large language models (LLMs) offer a promising avenue for mitigating vocabulary mismatch issues and thereby improving retrieval quality. Directly applying LLMs to sparse retrieval in product search exposes two key challenges:(1)Queries and product titles are typically short and highly susceptible to LLM-induced hallucinations, such as generating irrelevant expansion terms or underweighting critical literal terms like brand names and model numbers;(2)The large vocabulary space of LLMs leads to difficulty in initializing training effectively, making it challenging to learn meaningful sparse representations in such ultra-high-dimensional spaces.To address these challenges, we propose PROSPER, a framework for PROduct search leveraging LLMs as SParsE Retrievers. PROSPER incorporates: (1)A literal residual network that alleviates hallucination in lexical expansion by reinforcing underweighted literal terms through a residual compensation mechanism; and (2)A lexical focusing window that facilitates effective training initialization via a coarse-to-fine sparsification strategy.Extensive offline and online experiments show that PROSPER significantly outperforms sparse baselines and achieves recall performance comparable to advanced dense retrievers, while also achieving revenue increments online.
title LLMs as Sparse Retrievers:A Framework for First-Stage Product Search
topic Information Retrieval
url https://arxiv.org/abs/2510.18527