@inproceedings{agarwal-etal-2026-rear,
    title = "{RE}a{R} : Retrieve, Expand and Refine for Effective Multitable Retrieval",
    author = "Agarwal, Rishita  and
      Singhal, Himanshu  and
      Chen, Peter Baile  and
      Choudhury, Manan Roy  and
      Roth, Dan  and
      Gupta, Vivek",
    editor = "Liakata, Maria  and
      Moreira, Viviane P.  and
      Zhang, Jiajun  and
      Jurgens, David",
    booktitle = "Proceedings of the 64th Annual Meeting of the {A}ssociation for {C}omputational {L}inguistics (Volume 1: Long Papers)",
    month = jul,
    year = "2026",
    address = "San Diego, California, United States",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/ingest-acl/2026.acl-long.1826/",
    pages = "39360--39374",
    ISBN = "979-8-89176-390-6",
    abstract = "Answering natural language queries over relational data often requires retrieving and reasoning over multiple tables, yet most retrievers optimize only for query{--}table relevance and ignore table{--}table compatibility. We introduce REaR (Retrieve, Expand and Refine), a three-stage, LLM-free framework that separates semantic relevance from structural joinability for efficient, high-fidelity multi-table retrieval. REaR (i) retrieves query-aligned tables, (ii) expands these with structurally joinable tables via fast, precomputed column-embedding comparisons, and (iii) refines them by pruning noisy or weakly related candidates. Empirically, REaR is retriever-agnostic and consistently improves dense/ sparse retrievers on complex table QA datasets (BIRD, MMQA, and Spider) by improving both multi-table retrieval quality and downstream SQL execution. Despite being LLM-free, it delivers performance competitive with state-of-the-art LLM-augmented retrieval systems (e.g., ARM) while achieving much lower latency and cost. Ablations confirm complementary gains from expansion and refinement, underscoring REaR as a practical, scalable building block for table-based downstream tasks (e.g., Text-to-SQL)."
}