Saravan Rajmohan


2025

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WarriorCoder: Learning from Expert Battles to Augment Code Large Language Models
Huawen Feng | Pu Zhao | Qingfeng Sun | Can Xu | Fangkai Yang | Lu Wang | Qianli Ma | Qingwei Lin | Saravan Rajmohan | Dongmei Zhang | Qi Zhang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

Despite recent progress achieved by code large language models (LLMs), their remarkable abilities are largely dependent on fine-tuning on the high-quality data, posing challenges for data collection and annotation. To address this, current methods often design various data flywheels to collect complex code instructions, enabling models to handle more intricate tasks. However, these approaches typically rely on off-the-shelf datasets and data augmentation from a limited set of proprietary LLMs (e.g., Claude, GPT4, and so on), which restricts the diversity of the constructed data and makes it prone to systemic biases. In this paper, we propose **WarriorCoder**, a novel paradigm learns from expert battles to address these limitations. Specifically, we create an arena where leading expert code LLMs challenge each other, with evaluations conducted by impartial judges. This competitive framework generates novel training data from scratch, leveraging the strengths of all participants. Experimental results show that **WarriorCoder** achieves state-of-the-art performance compared to previous models of the same size, even without relying on proprietary LLMs.

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AXIS: Efficient Human-Agent-Computer Interaction with API-First LLM-Based Agents
Junting Lu | Zhiyang Zhang | Fangkai Yang | Jue Zhang | Lu Wang | Chao Du | Qingwei Lin | Saravan Rajmohan | Dongmei Zhang | Qi Zhang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

Multimodal large language models (MLLMs) have enabled LLM-based agents to directly interact with application user interfaces (UIs), enhancing agents’ performance in complex tasks. However, these agents often suffer from high latency and low reliability due to the extensive sequential UI interactions. To address this issue, we propose AXIS, a novel LLM-based agents framework that prioritize actions through application programming interfaces (APIs) over UI actions. This framework also facilitates the creation and expansion of APIs through automated exploration of applications. Our experiments on Microsoft Word demonstrate that AXIS reduces task completion time by 65%-70% and cognitive workload by 38%-53%, while maintaining accuracy of 97%-98% compared to humans. Our work contributes to a new human-agent-computer interaction (HACI) framework and explores a fresh UI design principle for application providers to turn applications into agents in the era of LLMs, paving the way towards an agent-centric operating system (Agent OS). The code and dataset will be available at https://aka.ms/haci_axis.

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Synergistic Weak-Strong Collaboration by Aligning Preferences
Yizhu Jiao | Xuchao Zhang | Zhaoyang Wang | Yubo Ma | Zhun Deng | Rujia Wang | Chetan Bansal | Saravan Rajmohan | Jiawei Han | Huaxiu Yao
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)

Current Large Language Models excel in general reasoning yet struggle with specialized tasks requiring proprietary or domain-specific knowledge. Fine-tuning large models for every niche application is often infeasible due to black-box constraints and high computational overhead. To address this, we propose a collaborative framework that pairs a specialized weak model with a general strong model. The weak model, tailored to specific domains, produces initial drafts and background information, while the strong model leverages its advanced reasoning to refine these drafts, extending LLMs’ capabilities to critical yet specialized tasks. To optimize this collaboration, we introduce a collaborative feedback to fine-tunes the weak model, which quantifies the influence of the weak model’s contributions in the collaboration procedure and establishes preference pairs to guide preference tuning of the weak model. We validate our framework through experiments on three domains. We find that the collaboration significantly outperforms each model alone by leveraging complementary strengths. Moreover, aligning the weak model with the collaborative preference further enhances overall performance.

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TACO-RL: Task Aware Prompt Compression Optimization with Reinforcement Learning
Shivam Shandilya | Menglin Xia | Supriyo Ghosh | Huiqiang Jiang | Jue Zhang | Qianhui Wu | Victor Rühle | Saravan Rajmohan
Findings of the Association for Computational Linguistics: ACL 2025

The increasing prevalence of large language models (LLMs) such as GPT-4 in various applications has led to a surge in the size of prompts required for optimal performance, leading to challenges in computational efficiency. Prompt compression aims to reduce the inference cost by minimizing input tokens without compromising on the task performance. However, existing prompt compression techniques either rely on sub-optimal metrics such as information entropy or model it as a task-agnostic token classification problem that fails to capture task-specific information.To address these issues, we propose a novel and efficient reinforcement learning (RL) based task-aware prompt compression method. To ensure low latency requirements, we leverage existing Transformer encoder-based token classification model while guiding the learning process with task-specific reward signals using lightweight REINFORCE algorithm. We evaluate the performance of our method on three diverse and challenging tasks including text summarization, question answering and code summarization. We demonstrate that our RL-guided compression method improves the task performance by 8% - 189% across these three scenarios over state-of-the-art compression techniques while satisfying the same compression rate and latency requirements.

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CARMO: Dynamic Criteria Generation for Context Aware Reward Modelling
Taneesh Gupta | Shivam Shandilya | Xuchao Zhang | Rahul Madhavan | Supriyo Ghosh | Chetan Bansal | Huaxiu Yao | Saravan Rajmohan
Findings of the Association for Computational Linguistics: ACL 2025

Reward modeling in large language models is known to be susceptible to reward hacking, causing models to latch onto superficial features such as the tendency to generate lists or unnecessarily long responses. In RLHF, and more generally during post-training, flawed reward signals often lead to outputs that optimize for these spurious correlates instead of genuine quality or correctness. We propose **Carmo (Context-Aware Reward Modeling)**, a novel approach that first generates dynamic, context-relevant criteria to ground the reward model prior to producing reward scores. Unlike prior methods that use static rubrics, Carmo leverages powerful LLMs to adaptively create evaluation criteria, e.g., logical consistency, clarity, and depth, tailored to the user query. Our theoretical analysis shows that such criteria generation can mitigate reward hacking. We further demonstrate how Carmo can be distilled into smaller models, thereby lowering the computational cost of alignment. We establish a new state-of-the-art performance on zero shot setting for generative models, with a 2.1% improvement on Reward Bench. Furthermore, alignment performed on the Carmo-curated preference dataset achieves **22.5% and 21.1% LC-WR (%) and WR (%) on Mistral-Base (7B)**. We release our datasets at [huggingface/CARMO](https://huggingface.co/datasets/Multi-preference-Optimization/CARMO-UltraFeedback).

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DI-BENCH: Benchmarking Large Language Models on Dependency Inference with Testable Repositories at Scale
Linghao Zhang | Junhao Wang | Shilin He | Chaoyun Zhang | Yu Kang | Bowen Li | Jiaheng Wen | Chengxing Xie | Maoquan Wang | Yufan Huang | Elsie Nallipogu | Qingwei Lin | Yingnong Dang | Saravan Rajmohan | Dongmei Zhang | Qi Zhang
Findings of the Association for Computational Linguistics: ACL 2025

Large Language Models have advanced automated software development, however, it remains a challenge to correctly infer dependencies, namely, identifying the internal components and external packages required for a repository to successfully run. Existing studies highlight that dependency-related issues cause over 40% of observed runtime errors on the generated repository. To address this, we introduce DI-BENCH, a large-scale benchmark and evaluation framework specifically designed to assess LLMs’ capability on dependency inference. The benchmark features 581 repositories with testing environments across Python, C#, Rust, and JavaScript. Extensive experiments with textual and execution-based metrics reveal that the current best-performing model achieves only a 48% execution pass rate on Python, indicating significant room for improvement. DI-BENCH establishes a new viewpoint for evaluating LLM performance on repositories, paving the way for more robust end-to-end software synthesis.

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UFO: A UI-Focused Agent for Windows OS Interaction
Chaoyun Zhang | Liqun Li | Shilin He | Xu Zhang | Bo Qiao | Si Qin | Minghua Ma | Yu Kang | Qingwei Lin | Saravan Rajmohan | Dongmei Zhang | Qi Zhang
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)

We introduce UFO, a UI-Fcused agent designed to fulfill user requests tailored to Windows OS applications by observing and analyzing the GUI and control information of these applications. UFO utilizes a hierarchical dual-agent framework that decomposes user requests using a divide-and-conquer approach, enabling seamless navigation and addressing sub-tasks across multiple applications. It also incorporates a control interaction module tailored for Windows OS, which detects control elements effectively and allows for fully automated execution. As a result, UFO simplifies complex and time-consuming processes into tasks that can be completed with natural language commands.We conducted testing of UFO across 9 popular Windows applications, encompassing a variety of scenarios. The results derived from both quantitative metrics and real-case studies, underscore the superior effectiveness of UFOin fulfilling user requests. To the best of our knowledge, UFO stands as the first UI agent specifically tailored for task completion within the Windows OS.

2024

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EfficientRAG: Efficient Retriever for Multi-Hop Question Answering
Ziyuan Zhuang | Zhiyang Zhang | Sitao Cheng | Fangkai Yang | Jia Liu | Shujian Huang | Qingwei Lin | Saravan Rajmohan | Dongmei Zhang | Qi Zhang
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing

Retrieval-augmented generation (RAG) methods encounter difficulties when addressing complex questions like multi-hop queries.While iterative retrieval methods improve performance by gathering additional information, current approaches often rely on multiple calls of large language models (LLMs).In this paper, we introduce EfficientRAG, an efficient retriever for multi-hop question answering.EfficientRAG iteratively generates new queries without the need for LLM calls at each iteration and filters out irrelevant information.Experimental results demonstrate that EfficientRAG surpasses existing RAG methods on three open-domain multi-hop question-answering datasets.The code is available in [aka.ms/efficientrag](https://github.com/NIL-zhuang/EfficientRAG-official).

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Hybrid-RACA: Hybrid Retrieval-Augmented Composition Assistance for Real-time Text Prediction
Menglin Xia | Xuchao Zhang | Camille Couturier | Guoqing Zheng | Saravan Rajmohan | Victor Rühle
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing: Industry Track

Large language models (LLMs) enhanced with retrieval augmentation has shown great performance in many applications. However, the computational demands for these models pose a challenge when applying them to real-time tasks, such as composition assistance. To address this, we propose Hybrid Retrieval-Augmented Composition Assistance (Hybrid-RACA), a novel system for real-time text prediction that efficiently combines a cloud-based LLM with a smaller client-side model through retrieval augmented memory. This integration enables the client model to generate better responses, benefiting from the LLM’s capabilities and cloud-based data. Meanwhile, via a novel asynchronous memory update mechanism, the client model can deliver real-time completions to user inputs without the need to wait for responses from the cloud. Our experiments on five datasets demonstrate that Hybrid-RACA offers strong performance while maintaining low latency.

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Everything of Thoughts: Defying the Law of Penrose Triangle for Thought Generation
Ruomeng Ding | Chaoyun Zhang | Lu Wang | Yong Xu | Minghua Ma | Wei Zhang | Si Qin | Saravan Rajmohan | Qingwei Lin | Dongmei Zhang
Findings of the Association for Computational Linguistics: ACL 2024

This paper introduce a novel thought prompting approach called ”Everything of Thoughts” (XoT) for Large Language Models (LLMs) to defy the law of ”Penrose triangle” of existing thought paradigms, to achieve three key perspectives in thought generation simultaneously: performance, efficiency, and flexibility. XoT leverages pretrained reinforcement learning and Monte Carlo Tree Search (MCTS) to incorporate external domain knowledge and planning capability into thoughts, thereby enhancing LLMs’ decision-making capabilities. Through the MCTS-LLM collaborative thought revision framework, XoT autonomously produces high-quality comprehensive cognitive mappings with minimal LLM interactions. Additionally, XoT empowers LLMs to utilize flexible cognitive mappings for solving problems with multiple solutions.We evaluate XoT on several challenging problem-solving tasks, including Game of 24, 8-Puzzle, and Pocket Cube. Our results demonstrate that XoT significantly outperforms existing approaches in various dimensions, showcasing its remarkable proficiency in addressing complex problems across diverse domains. The data and code are available at https://github.com/microsoft/Everything-of-Thoughts-XoT.

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Call Me When Necessary: LLMs can Efficiently and Faithfully Reason over Structured Environments
Sitao Cheng | Ziyuan Zhuang | Yong Xu | Fangkai Yang | Chaoyun Zhang | Xiaoting Qin | Xiang Huang | Ling Chen | Qingwei Lin | Dongmei Zhang | Saravan Rajmohan | Qi Zhang
Findings of the Association for Computational Linguistics: ACL 2024

Large Language Models (LLMs) have shown potential in reasoning over structured environments, e.g., knowledge graphs and tables. Such tasks typically require multi-hop reasoning, i.e., match natural language utterance with instances in the environment. Previous works adopt LLMs to incrementally build a reasoning path, where LLMs either invoke tools or pick up items by step-by-step interacting with the environment. We propose Reasoning-Path-Editing (Readi), a novel framework where LLMs can efficiently and faithfully reason over structured environments. In Readi, LLMs initially generate a reasoning path given a query, and edit the path only when necessary. We instantiate the path on structured environments and provide feedback to edit the path if anything goes wrong. Experimental results on three KGQA and two TableQA datasets show the effectiveness of Readi, significantly surpassing previous LLM-based methods (by 9.1% Hit@1 on WebQSP, 12.4% on MQA-3H and 9.5% on WTQ), comparable with state-of-the-art fine-tuned methods (67% on CWQ and 74.7% on WebQSP) and substantially boosting the vanilla LLMs (by 14.9% on CWQ). Our code will be available on https://aka.ms/readi.

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AutoRAG-HP: Automatic Online Hyper-Parameter Tuning for Retrieval-Augmented Generation
Jia Fu | Xiaoting Qin | Fangkai Yang | Lu Wang | Jue Zhang | Qingwei Lin | Yubo Chen | Dongmei Zhang | Saravan Rajmohan | Qi Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024

Recent advancements in Large Language Models have transformed ML/AI development, necessitating a reevaluation of AutoML principles for the Retrieval-Augmented Generation (RAG) systems. To address the challenges of hyper-parameter optimization and online adaptation in RAG, we propose the AutoRAG-HP framework, which formulates the hyper-parameter tuning as an online multi-armed bandit (MAB) problem and introduces a novel two-level Hierarchical MAB (Hier-MAB) method for efficient exploration of large search spaces. We conduct extensive experiments on tuning hyper-parameters, such as top-k retrieved documents, prompt compression ratio, and embedding methods, using the ALCE-ASQA and Natural Questions datasets. Our evaluation from jointly optimization all three hyper-parameters demonstrate that MAB-based online learning methods can achieve Recall@5 ≈ 0.8 for scenarios with prominent gradients in search space, using only ~20% of the LLM API calls required by the Grid Search approach. Additionally, the proposed Hier-MAB approach outperforms other baselines in more challenging optimization scenarios. The code will be made available at https://aka.ms/autorag.

2023

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Empower Large Language Model to Perform Better on Industrial Domain-Specific Question Answering
Fangkai Yang | Pu Zhao | Zezhong Wang | Lu Wang | Bo Qiao | Jue Zhang | Mohit Garg | Qingwei Lin | Saravan Rajmohan | Dongmei Zhang
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing: Industry Track

Large Language Model (LLM) has gained popularity and achieved remarkable results in open-domain tasks, but its performance in real industrial domain-specific scenarios is average due to its lack of specific domain knowledge. This issue has attracted widespread attention, but there are few relevant benchmarks available. In this paper, we provide a benchmark Question Answering (QA) dataset named MSQA, centered around Microsoft products and IT technical problems encountered by customers. This dataset contains industry cloud-specific QA knowledge, an area not extensively covered in general LLMs, making it well-suited for evaluating methods aiming to enhance LLMs’ domain-specific capabilities. In addition, we propose a new model interaction paradigm that can empower LLM to achieve better performance on domain-specific tasks where it is not proficient. Extensive experiments demonstrate that the approach following our method outperforms the commonly used LLM with retrieval methods. We make our source code and sample data available at: https://aka.ms/Microsoft_QA.