Leveraging Decoder Architectures for Learned Sparse Retrieval

Fuente: arXiv
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Auteurs principaux: Qiao, Jingfen, Nguyen, Thong, Kanoulas, Evangelos, Yates, Andrew
Format: Preprint
Publié: 2025
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author Qiao, Jingfen
Nguyen, Thong
Kanoulas, Evangelos
Yates, Andrew
author_facet Qiao, Jingfen
Nguyen, Thong
Kanoulas, Evangelos
Yates, Andrew
contents Learned Sparse Retrieval (LSR) has traditionally focused on small-scale encoder-only transformer architectures. With the advent of large-scale pre-trained language models, their capability to generate sparse representations for retrieval tasks across different transformer-based architectures, including encoder-only, decoder-only, and encoder-decoder models, remains largely unexplored. This study investigates the effectiveness of LSR across these architectures, exploring various sparse representation heads and model scales. Our results highlight the limitations of using large language models to create effective sparse representations in zero-shot settings, identifying challenges such as inappropriate term expansions and reduced performance due to the lack of expansion. We find that the encoder-decoder architecture with multi-tokens decoding approach achieves the best performance among the three backbones. While the decoder-only model performs worse than the encoder-only model, it demonstrates the potential to outperform when scaled to a high number of parameters.
format Preprint
id arxiv_https___arxiv_org_abs_2504_18151
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Leveraging Decoder Architectures for Learned Sparse Retrieval
Qiao, Jingfen
Nguyen, Thong
Kanoulas, Evangelos
Yates, Andrew
Information Retrieval
Learned Sparse Retrieval (LSR) has traditionally focused on small-scale encoder-only transformer architectures. With the advent of large-scale pre-trained language models, their capability to generate sparse representations for retrieval tasks across different transformer-based architectures, including encoder-only, decoder-only, and encoder-decoder models, remains largely unexplored. This study investigates the effectiveness of LSR across these architectures, exploring various sparse representation heads and model scales. Our results highlight the limitations of using large language models to create effective sparse representations in zero-shot settings, identifying challenges such as inappropriate term expansions and reduced performance due to the lack of expansion. We find that the encoder-decoder architecture with multi-tokens decoding approach achieves the best performance among the three backbones. While the decoder-only model performs worse than the encoder-only model, it demonstrates the potential to outperform when scaled to a high number of parameters.
title Leveraging Decoder Architectures for Learned Sparse Retrieval
topic Information Retrieval
url https://arxiv.org/abs/2504.18151