André Melo
Author directoryAlso published as: Andre Melo
2026
Gnosis Deepsearch: Structured Search Space Navigation for Complex QA
Umut Halil | Le Zhang | Jin Huang | Yuwei Zhang | Xinyu Hou | Andre Melo | Shriram Piramanayagam | Amela Fejza | Ruofei Lai | Yang Ren | Pavlos Vougiouklis | Jeff Z. Pan
Findings of the Association for Computational Linguistics: EMNLP 2026
Umut Halil | Le Zhang | Jin Huang | Yuwei Zhang | Xinyu Hou | Andre Melo | Shriram Piramanayagam | Amela Fejza | Ruofei Lai | Yang Ren | Pavlos Vougiouklis | Jeff Z. Pan
Findings of the Association for Computational Linguistics: EMNLP 2026
Complex, multi-step reasoning demands agents to be capable of dynamically exploring diverse research directions and adapting plans on the fly. We introduce Gnosis Deepsearch, a schema-guided framework for long-horizon planning in complex Question Answering, where variables, clues, and constraints are captured in a structured state representation maintained across trajectories. This state is cascaded into parallel search paths broadening exploration without relying on sequential execution, thereby mitigating both limited search space coverage and catastrophic forgetting. We couple Gnosis with a retriever that sidesteps challenges associated with retrieval and LLM reading when longer documents are involved. Our retrieval strategy ensures that the most relevant snippets from longer documents are considered, showcasing several benefits within both Gnosis and a more general ReAct framework on the BrowseComp-Plus benchmark. Extensive experiments on several QA benchmarks of varying difficulty demonstrate the strong performance of Gnosis across different configurations.
2025
GeAR: Graph-enhanced Agent for Retrieval-augmented Generation
Zhili Shen | Chenxin Diao | Pavlos Vougiouklis | Pascual Merita | Shriram Piramanayagam | Enting Chen | Damien Graux | Andre Melo | Ruofei Lai | Zeren Jiang | Zhongyang Li | Ye Qi | Yang Ren | Dandan Tu | Jeff Z. Pan
Findings of the Association for Computational Linguistics: ACL 2025
Zhili Shen | Chenxin Diao | Pavlos Vougiouklis | Pascual Merita | Shriram Piramanayagam | Enting Chen | Damien Graux | Andre Melo | Ruofei Lai | Zeren Jiang | Zhongyang Li | Ye Qi | Yang Ren | Dandan Tu | Jeff Z. Pan
Findings of the Association for Computational Linguistics: ACL 2025
Retrieval-augmented Generation (RAG) relies on effective retrieval capabilities, yet traditional sparse and dense retrievers inherently struggle with multi-hop retrieval scenarios. In this paper, we introduce GeAR, a system that advances RAG performance through two key innovations: (i) an efficient graph expansion mechanism that augments any conventional base retriever, such as BM25, and (ii) an agent framework that incorporates the resulting graph-based retrieval into a multi-step retrieval framework. Our evaluation demonstrates GeAR’s superior retrieval capabilities across three multi-hop question answering datasets. Notably, our system achieves state-of-the-art results with improvements exceeding 10% on the challenging MuSiQue dataset, while consuming fewer tokens and requiring fewer iterations than existing multi-step retrieval systems. The project page is available at https://gear-rag.github.io.
Don’t Forget the Base Retriever! A Low-Resource Graph-based Retriever for Multi-hop Question Answering
André Melo | Enting Chen | Pavlos Vougiouklis | Chenxin Diao | Shriram Piramanayagam | Ruofei Lai | Jeff Z. Pan
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track
André Melo | Enting Chen | Pavlos Vougiouklis | Chenxin Diao | Shriram Piramanayagam | Ruofei Lai | Jeff Z. Pan
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track
Traditional Retrieval-augmented Generation systems struggle with complex multi-hop questions, which often require reasoning over multiple passages. While GraphRAG approaches address these challenges, most of them rely on expensive LLM calls. In this paper, we propose GRiever, a lightweight, low-resource, multi-step graph-based retriever for multi-hop QA. Unlike prior work, GRiever does not rely on LLMs and can perform multi-step retrieval in a few hundred milliseconds. It efficiently indexes passages alongside an associated knowledge graph and employs a hybrid retriever combined with aggressive filtering to reduce retrieval latency. Experiments on multi-hop QA datasets demonstrate that GRiever outperforms conventional retrievers and shows strong potential as a base retriever within multi-step agentic frameworks.