LEGO: Synergizing Expert GraphRAG and Expert Chain-of-Thought for Legal Reasoning

arXiv:2609.27009 · cs.CL, cs.IR · Submitted 2026-09-22 · Read on arXiv

cs.CL, cs.IR

Submitted: 2026-09-22

Updated: 2026-10-04

Comments: Accepted to EMNLP 2026(Findings)

Code: https://github.com/BLK-WHT/LEGO

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Terminology

• RAG — 114× in this paper · explained in 3 episodes
• Accuracy — 33× in this paper · explained in 1 episode
• Benchmark — 33× in this paper · explained in 2 episodes
• Ablation — 30× in this paper · explained in 1 episode
• Consistency — 10× in this paper · explained in 3 episodes
• Trace — 9× in this paper · explained in 2 episodes
• Core — 7× in this paper · explained in 2 episodes
• Retrieval-Augmented Generation — 7× in this paper
• Robustness — 7× in this paper · explained in 5 episodes
• Knowledge Graph — 6× in this paper · explained in 7 episodes
• Failure Modes — 4× in this paper · explained in 3 episodes
• Normative Coverage Greedy — 4× in this paper
• Ablation study — 3× in this paper · explained in 1 episode
• Benchmarking — 3× in this paper · explained in 3 episodes
• Gap Closing Rate — 3× in this paper
• Ontology — 3× in this paper · explained in 2 episodes
• Transferability — 3× in this paper · explained in 4 episodes
• Additivity — 2× in this paper · explained in 1 episode
• Chain-of-Thought (CoT) — 2× in this paper · explained in 4 episodes
• Chain-of-Thought Prompting — 2× in this paper · explained in 2 episodes
• Clustering — 2× in this paper · explained in 2 episodes
• Graph Construction — 2× in this paper · explained in 3 episodes
• Grounding — 2× in this paper · explained in 3 episodes
• Multi-hop Reasoning — 2× in this paper · explained in 3 episodes
• Redundancy — 2× in this paper · explained in 2 episodes
• Semantic Similarity — 2× in this paper · explained in 2 episodes
• Ablation Studies — 1× in this paper · explained in 1 episode
• Abstraction — 1× in this paper · explained in 1 episode
• Accountability — 1× in this paper · explained in 2 episodes
• Actor — 1× in this paper · explained in 3 episodes
• Adam — 1× in this paper · explained in 2 episodes
• Adaptive Reasoning — 1× in this paper · explained in 2 episodes
• Aggregation — 1× in this paper · explained in 1 episode
• Alignment — 1× in this paper · explained in 1 episode
• Approximation Bound — 1× in this paper · explained in 1 episode
• Calibration — 1× in this paper · explained in 7 episodes
• Chain-of-Thought (CoT) Prompting — 1× in this paper · explained in 3 episodes
• Continual Learning — 1× in this paper · explained in 2 episodes
• Foundation Model — 1× in this paper · explained in 3 episodes
• Foundation Models — 1× in this paper · explained in 7 episodes
• Hallucination — 1× in this paper · explained in 3 episodes
• Interpretability — 1× in this paper · explained in 15 episodes
• Knowledge graphs — 1× in this paper · explained in 2 episodes
• LLM-as-a-Judge — 1× in this paper · explained in 3 episodes
• Pragmatics — 1× in this paper · explained in 2 episodes
• Prompt Engineering — 1× in this paper · explained in 4 episodes
• Retrieval-Augmented Generation (RAG) — 1× in this paper · explained in 16 episodes
• Structural Reasoning — 1× in this paper · explained in 2 episodes
• Thinking mode — 1× in this paper · explained in 2 episodes
• Verification — 1× in this paper · explained in 2 episodes
• Verifier — 1× in this paper · explained in 2 episodes

Sources

• HuatuoGPT-o1, Towards Medical Complex Reasoning with LLMs
• DeepSeek-V3 Technical Report
• From Local to Global: A Graph RAG Approach to Query-Focused Summarization
• Expert-Guided Prompting and Retrieval-Augmented Generation for Emergency Medical Service Question Answering
• From RAG to Memory: Non-Parametric Continual Learning for Large Language Models
• LegalOne: A Family of Foundation Models for Reliable Legal Reasoning
• Qwen3 Technical Report
• RAPTOR: Recursive Abstractive Processing for Tree-Organized Retrieval
• OMD-GraphRAG: Enhancing GraphRAG with Ontology-Guided Extraction, Multi-Dimensional Clustering and Dual-Channel Fusion
• RAT: Retrieval Augmented Thoughts Elicit Context-Aware Reasoning in Long-Horizon Generation
• Benchmarking Multi-Step Legal Reasoning and Analyzing Chain-of-Thought Effects in Large Language Models
• A Survey of Graph Retrieval-Augmented Generation for Customized Large Language Models
• LinearRAG: Linear Graph Retrieval Augmented Generation on Large-scale Corpora

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