@inproceedings{yang-etal-2026-reloop,
title = "{RELOOP}: Recursive Retrieval with Multi-Hop Reasoner and Planners for Heterogeneous {QA}",
author = "Yang, Ruiyi and
Xue, Hao and
Razzak, Imran and
Hacid, Hakim and
Salim, Flora D.",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {EMNLP} 2026",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-emnlp.1736/",
pages = "37120--37138",
ISBN = "979-8-89176-462-0",
abstract = "Retrieval-augmented generation (RAG) remains challenging for multi-hop question answering when supporting evidence is distributed across heterogeneous sources, including text, tables, and knowledge graphs (KGs). Existing systems often rely on modality-specific retrieval pipelines or uncontrolled iterative search, making it difficult to preserve source structure while maintaining efficient evidence acquisition. We present **RELOOP**, a structure-aware retrieval framework built on **Hierarchical Sequence (HSEQ)**, a reversible representation that maps heterogeneous sources into provenance-preserving typed segments with lightweight structural links. Operating on this unified evidence interface, a lightweight iterator selects and expands candidate evidence through structure-respecting actions, while an explicit sufficiency signal determines when the accumulated evidence is adequate for answering. A head module then synthesizes the final answer from a compact, canonicalized evidence package, with an optional refinement step when inconsistent evidence is detected. Experiments on HotpotQA, HybridQA, TAT-QA, and MetaQA show that RELOOP consistently improves answer quality over strong single-pass and iterative RAG baselines while requiring substantially fewer retrieval steps than graph-expansion approaches. These results suggest that a reversible, structure-aware evidence interface provides an effective foundation for accurate and budget-controlled retrieval across heterogeneous QA settings."
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<abstract>Retrieval-augmented generation (RAG) remains challenging for multi-hop question answering when supporting evidence is distributed across heterogeneous sources, including text, tables, and knowledge graphs (KGs). Existing systems often rely on modality-specific retrieval pipelines or uncontrolled iterative search, making it difficult to preserve source structure while maintaining efficient evidence acquisition. We present **RELOOP**, a structure-aware retrieval framework built on **Hierarchical Sequence (HSEQ)**, a reversible representation that maps heterogeneous sources into provenance-preserving typed segments with lightweight structural links. Operating on this unified evidence interface, a lightweight iterator selects and expands candidate evidence through structure-respecting actions, while an explicit sufficiency signal determines when the accumulated evidence is adequate for answering. A head module then synthesizes the final answer from a compact, canonicalized evidence package, with an optional refinement step when inconsistent evidence is detected. Experiments on HotpotQA, HybridQA, TAT-QA, and MetaQA show that RELOOP consistently improves answer quality over strong single-pass and iterative RAG baselines while requiring substantially fewer retrieval steps than graph-expansion approaches. These results suggest that a reversible, structure-aware evidence interface provides an effective foundation for accurate and budget-controlled retrieval across heterogeneous QA settings.</abstract>
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%0 Conference Proceedings
%T RELOOP: Recursive Retrieval with Multi-Hop Reasoner and Planners for Heterogeneous QA
%A Yang, Ruiyi
%A Xue, Hao
%A Razzak, Imran
%A Hacid, Hakim
%A Salim, Flora D.
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Findings of the Association for Computational Linguistics: EMNLP 2026
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-462-0
%F yang-etal-2026-reloop
%X Retrieval-augmented generation (RAG) remains challenging for multi-hop question answering when supporting evidence is distributed across heterogeneous sources, including text, tables, and knowledge graphs (KGs). Existing systems often rely on modality-specific retrieval pipelines or uncontrolled iterative search, making it difficult to preserve source structure while maintaining efficient evidence acquisition. We present **RELOOP**, a structure-aware retrieval framework built on **Hierarchical Sequence (HSEQ)**, a reversible representation that maps heterogeneous sources into provenance-preserving typed segments with lightweight structural links. Operating on this unified evidence interface, a lightweight iterator selects and expands candidate evidence through structure-respecting actions, while an explicit sufficiency signal determines when the accumulated evidence is adequate for answering. A head module then synthesizes the final answer from a compact, canonicalized evidence package, with an optional refinement step when inconsistent evidence is detected. Experiments on HotpotQA, HybridQA, TAT-QA, and MetaQA show that RELOOP consistently improves answer quality over strong single-pass and iterative RAG baselines while requiring substantially fewer retrieval steps than graph-expansion approaches. These results suggest that a reversible, structure-aware evidence interface provides an effective foundation for accurate and budget-controlled retrieval across heterogeneous QA settings.
%U https://aclanthology.org/2026.findings-emnlp.1736/
%P 37120-37138
Markdown (Informal)
[RELOOP: Recursive Retrieval with Multi-Hop Reasoner and Planners for Heterogeneous QA](https://aclanthology.org/2026.findings-emnlp.1736/) (Yang et al., Findings 2026)
ACL