Hejia Geng
Author directory2026
An Automated Pipeline for Provably Retrieval-Dependent Benchmark Construction over Dynamic Knowledge
Heng Zhou | Ao Yu | Yuchen Fan | Li Kang | Jianing Shi | Yongting Zhang | Yutao Fan | Tiancheng He | Yibing Lin | Hejia Geng | Yuhao Wu | Xiufeng Song | Zhemeng Zhang | Songtao Huang | Yiran Qin | Wenlong Zhang | Lei Bai | Zhenfei Yin
Findings of the Association for Computational Linguistics: EMNLP 2026
Heng Zhou | Ao Yu | Yuchen Fan | Li Kang | Jianing Shi | Yongting Zhang | Yutao Fan | Tiancheng He | Yibing Lin | Hejia Geng | Yuhao Wu | Xiufeng Song | Zhemeng Zhang | Songtao Huang | Yiran Qin | Wenlong Zhang | Lei Bai | Zhenfei Yin
Findings of the Association for Computational Linguistics: EMNLP 2026
Static benchmarks often conflate memorization with reasoning, failing to capture the dynamic nature of world knowledge. We present LiveSearchBench, a scalable pipeline that automatically constructs snapshot-grounded benchmarks from knowledge graph differentials, in which every answer is unique and SPARQL-verifiable against a target snapshot. Unlike prior template-based approaches, our method leverages topology-aware synthesis to generate multi-constraint compositional questions with unique answers guaranteed via SPARQL validation. Evaluating 1,000 questions across three difficulty levels on both open-weight and frontier models, we expose a pronounced Recency Gap on facts that post-date a model’s training cutoff, particularly for compositional queries; retrieval dependence is thus an empirical property we measure, not a formal guarantee we claim. Through Oracle and Wikidata-as-corpus analyses, we disentangle dual failure modes: retrieval coverage limitations for single-hop questions and reasoning failures for compositional queries even with ground-truth evidence. LiveSearchBench provides both a rigorous construction methodology and a continuously updatable testbed for evaluating evidence integration under evolving knowledge.
PAPO: Stabilizing Rubric Integration Training via Decoupled Advantage Normalization
Zelin Tan | Zhouliang Yu | Bohan Lin | Zijie Geng | Hejia Geng | Yudong Zhang | Mulei Zhang | Yang Chen | Shuyue Hu | Zhenfei Yin | Chen Zhang | Lei Bai
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Zelin Tan | Zhouliang Yu | Bohan Lin | Zijie Geng | Hejia Geng | Yudong Zhang | Mulei Zhang | Yang Chen | Shuyue Hu | Zhenfei Yin | Chen Zhang | Lei Bai
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
We propose Process-Aware Policy Optimization (PAPO), a method that integrates process-level evaluation into Group Relative Policy Optimization (GRPO) through **decoupled advantage normalization**, to address two limitations of existing reward designs. Outcome reward models (ORM) evaluate only final-answer correctness, treating all correct responses identically, and gradually lose the advantage signal as groups become uniformly correct. Rubric-based process reward models (PRM) offer richer supervision, differentiating quality among correct responses and restoring advantage diversity, but using their scores as rewards triggers verbosity-driven reward hacking and accuracy collapse. PAPO resolves both by composing the advantage from an outcome advantage Aout, derived from outcome reward rout over all responses, and a process advantage Aproc, derived from process reward rproc exclusively over the correct subset. Aout anchors correctness, and correct subset normalization on Aproc rules out verbosity-driven hacking while sustaining the gradient on all-correct groups where ORM exhausts. PAPO consistently outperforms ORM across five model configurations and six benchmarks (reaching 51.3% vs. 46.3% on OlympiadBench for Qwen2.5-7B while continuing to improve as ORM plateaus and declines), with analogous gains when composed with mainstream GRPO variants.
LatticeMind: A Conflict-Aware Memory Primitive for Multi-Agent Systems
Heng Zhou | Lian Zhang | Yutao Fan | Tiancheng He | Siki Chen | Hejia Geng | Philip Torr | Zhenfei Yin
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Heng Zhou | Lian Zhang | Yutao Fan | Tiancheng He | Siki Chen | Hejia Geng | Philip Torr | Zhenfei Yin
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Multi-agent LLM systems often fail not for lack of candidate answers, but because they have no persistent mechanism for deciding which incompatible claim should currently be trusted. Majority vote, debate, and judge-based selection choose an output without recording which claim wins, which is contested, or why a later update supersedes it. We present LatticeMind, a conflict-aware structured memory that handles contradiction at write time. It maintains explicit item status, applies cheap symbolic conflict checks, and routes the flagged cases to an LLM reconciler. On a label-blind ConflictBank evaluation that removes source-name hints, over a uniform draw of 200 examples from the full benchmark pool, LatticeMind reaches 0.965 accuracy versus 0.525 for the strongest baseline, with every gap significant at p<10-24 by paired McNemar test. Ablations show that removing the checker or the reconciler costs 12 to 14 points. Our claims are scoped to credibility conflicts, where one claim should defeat another: the coordination branch of the design is a safety override that we do not validate empirically, and all prompt-based comparisons are conditioned on a single backbone. On three secondary planning benchmarks and one synthetic scheduling diagnostic the picture is mixed: LatticeMind beats naive merge on three of four, but does not replace deliberation methods on tasks rewarding iterative search.
Parthenon Law: A Self-Evolving Legal-Agent Framework
Hejia Geng | Yuxuan Liu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
Hejia Geng | Yuxuan Liu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing: Industry Track
As agents grow more capable, legal-domain LLM agents promise to turn document-heavy matters into reviewable work products—yet reliable deployment faces three obstacles: no large-scale evidence on how today’s strongest model-and-harness combinations behave on end-to-end legal matters; no agent architecture adapted to the legal vertical, only general-purpose harnesses; and, in a setting that keeps shifting with new facts, authorities, and deadlines, no mechanism for systems to learn from their own outcomes. We address each. A large-scale empirical study on Harvey LAB—12,510 agent trajectories—shows that even frontier agents remain far from completing matters in a single pass: per-criterion accuracy climbs with stronger models while strict matter completion stalls. We then introduce Parthenon, a self-evolving legal-agent framework that factors Model, Harness, Agent roles, legal Knowledge, deterministic Tools, and procedural Skills into auditable surfaces for source traceability, date and number grounding, deliverable compliance, and issue closure. Finally, an anti-leakage learning loop converts scored failures into task-agnostic edits to skills, tools, and knowledge, letting the system improve with experience—as a firm refines its checklists and playbooks after each matter—without touching model weights. Across our large-scale empirical analysis, Parthenon substantially improves the performance of state-of-the-art models and harnesses on legal-matter tasks.
Scaling Behaviors of LLM Reinforcement Learning Post-Training: An Empirical Study in Mathematical Reasoning
Zelin Tan | Hejia Geng | Xiaohang Yu | Mulei Zhang | Guancheng Wan | Yifan Zhou | Qiang He | Xiangyuan Xue | Heng Zhou | Yutao Fan | Zhong-Zhi Li | Zaibin Zhang | Guibin Zhang | Chen Zhang | Zhenfei Yin | Philip Torr | Lei Bai
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Zelin Tan | Hejia Geng | Xiaohang Yu | Mulei Zhang | Guancheng Wan | Yifan Zhou | Qiang He | Xiangyuan Xue | Heng Zhou | Yutao Fan | Zhong-Zhi Li | Zaibin Zhang | Guibin Zhang | Chen Zhang | Zhenfei Yin | Philip Torr | Lei Bai
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
While scaling laws for large language models (LLMs) during pre-training have been extensively studied, their behavior under reinforcement learning (RL) post-training remains largely unexplored. This paper investigates the scaling behavior of Large Language Model (LLM) reinforcement learning post-training, focusing on mathematical reasoning. Through experiments across the Qwen2.5 series (0.5B to 72B), we characterize how model scale, data, and compute interact. Our analysis yields four key findings: 1. Larger models consistently demonstrate superior compute and data efficiency. 2. The relationship between model performance and training resources follows a predictive power-law across both base and instruction-tuned models. 3. RL learning efficiency exhibits a latent saturation trend with increasing model scale. 4. In data-constrained regimes, performance is primarily driven by the total volume of training data rather than sample uniqueness. These results offer practical guidelines for scaling reasoning capabilities through reinforcement learning post-training.
2025
ReSo: A Reward-driven Self-organizing LLM-based Multi-Agent System for Reasoning Tasks
Heng Zhou | Hejia Geng | Xiangyuan Xue | Li Kang | Yiran Qin | Zhiyong Wang | Zhenfei Yin | Lei Bai
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Heng Zhou | Hejia Geng | Xiangyuan Xue | Li Kang | Yiran Qin | Zhiyong Wang | Zhenfei Yin | Lei Bai
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Multi-agent systems have emerged as a promising approach for enhancing the reasoning capabilities of large language models in complex problem-solving. However, current MAS frameworks are limited by poor flexibility and scalability, with underdeveloped optimization strategies. To address these challenges, we propose ReSo, which integrates task graph generation with a reward-driven two-stage agent selection process. The core of ReSo is the proposed Collaborative Reward Model, which can provide fine-grained reward signals for MAS cooperation for optimization. We also introduce an automated data synthesis framework for generating MAS benchmarks, without human annotations. Experimentally, ReSo matches or outperforms existing methods. ReSo achieves 33.7% and 32.3% accuracy on Math-MAS and SciBench-MAS SciBench, while other methods completely fail. The code and data are available at Reso.
Search
Fix author
Co-authors
- Zhenfei Yin 5
- Lei Bai 4
- Heng Zhou 4
- Yutao Fan 3
- Tiancheng He 2
- Li Kang 2
- Yiran Qin 2
- Zelin Tan 2
- Philip Torr 2
- Xiangyuan Xue 2
- Chen Zhang 2
- Mulei Zhang 2
- Siki Chen 1
- Yang Chen 1
- Yuchen Fan 1
- Zijie Geng 1
- Qiang He 1
- Shuyue Hu 1
- Songtao Huang 1
- Zhong-Zhi Li 1
- Bohan Lin 1
- Yibing Lin 1
- Yuxuan Liu 1
- Jianing Shi 1
- Xiufeng Song 1
- Guancheng Wan 1
- Zhiyong Wang 1
- Yuhao Wu 1
- Ao Yu 1
- Xiaohang Yu 1
- Zhouliang Yu 1
- Guibin Zhang 1
- Lian Zhang 1
- Wenlong Zhang 1
- Yongting Zhang 1
- Yudong Zhang 1
- Zaibin Zhang 1
- Zhemeng Zhang 1
- Yifan Zhou 1