TRIAL: Token Relations and Importance Aware Late-interaction for Accurate Text Retrieval

AbstractLate-interaction based multi-vector retrieval systems have greatly advanced the field of information retrieval by enabling fast and accurate search over millions of documents. However, these systems rely on a naive summation of token-level similarity scores which often leads to inaccurate relevance estimation caused by the tokenization of semantic units (e.g., words and phrases) and the influence of low-content words (e.g., articles and prepositions). To address these challenges, we propose **TRIAL**: **T**oken **R**elations and **I**mportance **A**ware **L**ate-interaction, which enhances late interaction by explicitly modeling token relations and token importance in relevance scoring. Extensive experiments on three widely used benchmarks show that TRIAL achieves state-of-the-art accuracy, with an nDCG@10 of 46.3 on MSMARCO (in-domain), and average nDCG@10 scores of 51.09 and 72.15 on BEIR and LoTTE Search (out-of-domain), respectively. With superior accuracy, TRIAL maintains competitive retrieval speed compared to existing late-interaction methods, making it a practical solution for large-scale text retrieval.