DeepWeaver: Bridging the Evidence Synthesis Gap in Open-Ended Question Answering
Organizations: Department of Computer Science and Technology, Tsinghua University
Abstract
Retrieve-then-generate pipelines are commonly used to produce deep-research answers for open-ended questions, but retrieval alone is insufficient: LLMs must organize noisy and fragmented evidence into comprehensive, well-cited answers. We refer to this process as evidence synthesis. However, direct generation often underuses evidence, misaligns citations, and collapses diverse information into shallow summaries, exposing an evidence synthesis gap between retrieval and generation. Thus, we propose DeepWeaver, a novel framework that weaves noisy retrieved evidence into comprehensive answers by maintaining Thought Block Chains (TBCs), a structured representation that groups claims, salient information, keywords, and supporting evidence. DeepWeaver uses subordinate TBCs to inspect residual evidence, commit TBC revisions, and discover new claims before final generation. We evaluate DeepWeaver on open-ended QA over both knowledge bases and the web, and introduce LoQA, a high-density benchmark for evidence synthesis. Across multiple LLMs, DeepWeaver improves content sufficiency, citation grounding, and detail preservation on LoQA, while achieving deeper insights and higher citation quality on DeepResearch Bench. These results show that evidence weaving is an effective mechanism for bridging retrieval and generation in open-ended QA. Our code is available at https://github.com/KlozeWang/DeepWeaver.
Figures & tables
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
| Statistic | Value |
| # Questions | 100 |
| Avg. evidence tokens / question | 206,550.41 |
| Avg. relevant chunks / question | 91.79 |
| Avg. scoring points / question | 20.45 |
| Avg. cloze blanks / question | 47.79 |
| Avg. reference-answer tokens / question | 9,858.64 |
| Benchmark | Task Focus | Evidence Setting | Main Difference from LoQA |
| ALCE ( Gao et al., 2023 ) | Citation-grounded text generation | Retrieval corpora built from ASQA, QAMPARI, and ELI5 | Focuses on fluency, correctness, and citation quality. Its tasks primarily involve producing short answers or entity lists from retrieved passages, whereas LoQA targets comprehensive answers grounded in knowledge-intensive evidence pools of approximately 200K tokens. |
| FreshWiki ( Shao et al., 2024 ) | Wikipedia-like article generation from scratch | Web sources collected during the pre-writing stage | Evaluates whether systems can research a topic, construct an outline, and generate Wikipedia-like articles. In contrast, LoQA uses a noisy evidence pool and emphasizes comprehensive evidence synthesis in question answering, rather than outline construction or survey writing. |
| LongBench ( Bai et al., 2024 ) | Long-context understanding | Single-document QA, multi-document QA, summarization, few-shot learning, synthetic and code tasks | Assesses general long-context capability, but most tasks require short-form outputs or automatically verifiable answers rather than open-ended long-form answers. |
| L-Eval ( An et al., 2024 ) | Long-context model evaluation | Long documents across diverse domains and task types | Covers long-context QA and generation, but many tasks focus on short factual verification, extractive QA, or summarization rather than comprehensive open-ended answering. |
| InfiniteBench ( Zhang et al., 2024a ) | Extremely long-context processing | 100K+ token contexts across retrieval, code, math, novels, and dialogue | Stresses context length and reasoning capacity, but its targets are mainly verifiable short answers instead of long-form citation-grounded answers. |
| Loong ( Wang et al., 2024b ) | Extended multi-document QA | Multiple relevant documents where missing any document may hurt the answer | Emphasizes reasoning over all relevant documents, while LoQA further introduces noisy irrelevant evidence and evaluates citation grounding, content sufficiency, and detail preservation. |
| Statistic | Value |
| Avg. first-level outline node / question | 4.41 |
| Avg. routed outline node / question | 2.35 |
| Avg. routed-item ratio / question | 59.39% |
| Avg. evidence fragments / item | 88.92 |
| Avg. evidence fragments / routed item | 98.00 |
| Avg. raw tokens of evidence / routed item | 92,752.79 |
Evidence-Grounded Generation
Evidence-grounded generation produces answers and documents whose claims are supported by traceable sources.
See all 148 papers