Logic Tree: Topology-Aware Backtracking for DeepResearch Agents

Tianwen Lyu, Zhengke Gui, Peilong Zhao, Ling Zhong, Yiwen Zhang, Lei Liang, Mengshu Sun, Jun Zhou, Qiang Zhang, Huajun Chen


Abstract
Autonomous large language model (LLM) agents have shown strong potential for open-ended information-seeking tasks. However, existing agent frameworks primarily rely on sequential execution, making them vulnerable to error accumulation in long-horizon reasoning. Recent plan-and-execute approaches partially alleviate this issue, but their fixed planning strategies still struggle to recover from intermediate failures. We propose Logic Tree, a non-linear agentic reasoning framework formulated as a Directed Acyclic Graph (DAG). Instead of following a fixed plan with sequential execution, Logic Tree models complex task solving as a dynamically evolving and recoverable graph search process. The framework decomposes queries into parallel execution branches and incorporates a two-level self-correction mechanism. Local backtracking performs targeted rollback to repair failed reasoning states, while global replanning revises high-level execution strategies and preserves verified intermediate conclusions through a knowledge sanitation process. Experiments on BrowseComp, GAIA, and XBench show that Logic Tree consistently outperforms both sequential and plan-and-execute baselines. Further ablation studies demonstrate that combining DAG-based parallel execution with dynamic error recovery substantially improves robustness in long-horizon research tasks.
Anthology ID:
2026.findings-emnlp.844
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
17837–17856
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.844/
DOI:
Bibkey:
Cite (ACL):
Tianwen Lyu, Zhengke Gui, Peilong Zhao, Ling Zhong, Yiwen Zhang, Lei Liang, Mengshu Sun, Jun Zhou, Qiang Zhang, and Huajun Chen. 2026. Logic Tree: Topology-Aware Backtracking for DeepResearch Agents. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 17837–17856, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Logic Tree: Topology-Aware Backtracking for DeepResearch Agents (Lyu et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.844.pdf