ColBERT's [MASK]-based Query Augmentation: Effects of Quadrupling the Query Input Length

Fuente: arXiv
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Autori principali: Giacalone, Ben, Zanibbi, Richard
Natura: Preprint
Pubblicazione: 2024
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author Giacalone, Ben
Zanibbi, Richard
author_facet Giacalone, Ben
Zanibbi, Richard
contents A unique aspect of ColBERT is its use of [MASK] tokens in queries to score documents (query augmentation). Prior work shows [MASK] tokens weighting non-[MASK] query terms, emphasizing certain tokens over others , rather than introducing whole new terms as initially proposed. We begin by demonstrating that a term weighting behavior previously reported for [MASK] tokens in ColBERTv1 holds for ColBERTv2. We then examine the effect of changing the number of [MASK] tokens from zero to up to four times past the query input length used in training, both for first stage retrieval, and for scoring candidates, observing an initial decrease in performance with few [MASK]s, a large increase when enough [MASK]s are added to pad queries to an average length of 32, then a plateau in performance afterwards. Additionally, we compare baseline performance to performance when the query length is extended to 128 tokens, and find that differences are small (e.g., within 1% on various metrics) and generally statistically insignificant, indicating performance does not collapse if ColBERT is presented with more [MASK] tokens than expected.
format Preprint
id arxiv_https___arxiv_org_abs_2408_13672
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle ColBERT's [MASK]-based Query Augmentation: Effects of Quadrupling the Query Input Length
Giacalone, Ben
Zanibbi, Richard
Information Retrieval
H.3.3
A unique aspect of ColBERT is its use of [MASK] tokens in queries to score documents (query augmentation). Prior work shows [MASK] tokens weighting non-[MASK] query terms, emphasizing certain tokens over others , rather than introducing whole new terms as initially proposed. We begin by demonstrating that a term weighting behavior previously reported for [MASK] tokens in ColBERTv1 holds for ColBERTv2. We then examine the effect of changing the number of [MASK] tokens from zero to up to four times past the query input length used in training, both for first stage retrieval, and for scoring candidates, observing an initial decrease in performance with few [MASK]s, a large increase when enough [MASK]s are added to pad queries to an average length of 32, then a plateau in performance afterwards. Additionally, we compare baseline performance to performance when the query length is extended to 128 tokens, and find that differences are small (e.g., within 1% on various metrics) and generally statistically insignificant, indicating performance does not collapse if ColBERT is presented with more [MASK] tokens than expected.
title ColBERT's [MASK]-based Query Augmentation: Effects of Quadrupling the Query Input Length
topic Information Retrieval
H.3.3
url https://arxiv.org/abs/2408.13672