Publications

Full list of research papers, preprints, and publications

2026

Computer-Use Agents Are Embodied Generalists

Computer-Use Agents Are Embodied Generalists

Pranjal Aggarwal, Sean Welleck

Preprint2026

We argue that embodied tasks can be framed as interaction with software. We build software that renders an agent's view of a physical environment on a screen and provides controls for acting in it, so a computer-use agent can perform embodied tasks with the same screenshots, keyboard and mouse actions it uses on ordinary software. Using a single agent design and changing only the software, our entries placed first, second, third and sixth in four ECCV 2026 workshop competitions, without any competition-specific agent tuning.

Visual Token Routing: Learning to Keep Tokens That Matter

Visual Token Routing: Learning to Keep Tokens That Matter

Pranjal Aggarwal, Sean Welleck

arXiv2026

Computer-use agents represent each screenshot as thousands of visual tokens, and most of these tokens are either irrelevant to the next action or repeated across screenshots. We introduce Visual Token Routing (VTR), which trains the vision-language model together with a lightweight spatio-temporal router that decides which visual tokens enter the language model. With just 2,000 training steps, VTR matches the full-resolution model on OSWorld, CUA-World, and video game action prediction while using 2.5-5.8x fewer visual tokens, which cuts inference cost by up to 3.3x.

Gym-Anything for Robotics: Scaling Physical Simulations with Digital Agents

Gym-Anything for Robotics: Scaling Physical Simulations with Digital Agents

Pranjal Aggarwal, Sean Welleck

arXiv2026

We introduce Gym-Anything for Robotics, a framework in which coding agents create realistic robotics simulations, so improvements in coding agents translate directly into richer and more faithful simulations. Using an adversarial creation-audit loop, we build RoboWorld, a set of 25 simulations grounded in U.S. GDP data with 25 test and 175 training RL environments. Even the best frontier models fail on every RoboWorld test task, and we show several ways to improve them, including in-context learning, privileged teachers, and code policies that generate demonstrations for training vision-language-action models.

Gym-Anything-RT: Scaling Real-Time Environments for Vision-Language Agents

Gym-Anything-RT: Scaling Real-Time Environments for Vision-Language Agents

Pranjal Aggarwal, Sean Welleck

arXiv2026

We introduce Gym-Anything-RT, an agentic pipeline that generates visual minigames testing the capabilities AI agents need for real-time interaction, such as acting while the environment changes. The same minigame can be run in real time, slowed down, or paused, which allows controlled comparisons. On 100 generated minigames, GPT-6 Astra (xHigh) passes only 9.0% of the minigames in real time, compared with 75.0% when the environment is paused.

cua-speedrun: Standardized Benchmarking of the Speed of Computer-Use Agents

cua-speedrun: Standardized Benchmarking of the Speed of Computer-Use Agents

Pranjal Aggarwal, Lawrence Keunho Jang, Sean Welleck, Daniel Fried, Ruslan Salakhutdinov, Jing Yu Koh

arXiv2026

Speed and cost are key barriers to deploying computer-use agents, but current benchmarks run on varying infrastructure that makes speed hard to measure. We introduce cua-speedrun, which provides a uniform virtual machine setup, execution pipeline, and agent interface for measuring the performance, speed, and cost of CUAs across four benchmarks. We find that no single model family is best on all three, and that for some models more reasoning effort can make tasks finish faster.

Gym-Anything: Turn Any Software into an Agent Environment

Gym-Anything: Turn Any Software into an Agent Environment

Pranjal Aggarwal, Graham Neubig, Sean Welleck

NeurIPS2026Best Paper, Lifelong Agents Workshop @ COLM 2026Oral, SCALE@ICML 2026

We introduce Gym-Anything, a framework that turns any software into a computer-use agent environment with a simple make() call. The system includes 200+ real-world applications across 22 occupational categories, generating 10,000+ tasks with checklist-based verification. We also introduce CUA-World-Long, a benchmark of 200 long-horizon tasks evaluating agents on 500+ step interactions.

OptimalThinkingBench: Evaluating Over and Underthinking in LLMs

OptimalThinkingBench: Evaluating Over and Underthinking in LLMs

Pranjal Aggarwal, Seungone Kim, Jack Lanchantin, Sean Welleck, Jason Weston, Ilia Kulikov, Swarnadeep Saha

ICLR2026

Thinking LLMs solve complex tasks at the expense of increased compute and overthinking on simpler problems, while non-thinking LLMs are faster and cheaper but underthink on harder reasoning problems. We introduce OptimalThinkingBench, a unified benchmark that jointly evaluates overthinking and underthinking in LLMs and also encourages the development of optimally-thinking models that balance performance and efficiency. Our benchmark comprises two sub-benchmarks: OverthinkingBench, featuring simple math and general queries in 72 domains, and UnderthinkingBench, containing 11 challenging reasoning tasks along with harder math problems. Using novel thinking-adjusted accuracy metrics, we extensively evaluate 33 different thinking and non-thinking models and show that no model is able to optimally think on our benchmark.

Programming with Pixels: Can Computer-Use Agents do Software Engineering?

Programming with Pixels: Can Computer-Use Agents do Software Engineering?

Pranjal Aggarwal, Sean Welleck

ICLR2026

Computer-use agents (CUAs) hold the promise of performing a wide variety of general tasks, but current evaluations have primarily focused on simple scenarios. We introduce Programming with Pixels (PwP), the first comprehensive computer-use environment for software engineering, where agents visually control an IDE to perform diverse software engineering tasks. We introduce PwP-Bench, a benchmark of 15 existing and new software-engineering tasks spanning multiple modalities, programming languages, and skillsets. We find that when interacting purely visually, CUAs perform significantly worse than specialized coding agents. However, when given direct access to just two APIs -- file editing and bash operations -- performance jumps, often reaching the levels of specialized agents despite having a task-agnostic design.

Propose, Solve, Verify: Self-Play Through Formal Verification

Propose, Solve, Verify: Self-Play Through Formal Verification

Alex Wilf, Pranjal Aggarwal, Bryan Parno, Daniel Fried, Louis-Philippe Morency, Paul Pu Liang, Sean Welleck

ICML2026

We study self-play in the verified code generation setting, where formal verification provides reliable correctness signals. We introduce Propose, Solve, Verify (PSV), a simple self-play framework where formal verification signals are used to create a proposer capable of generating challenging synthetic problems and a solver trained via expert iteration. We use PSV to train PSV-Verus, which across three benchmarks improves pass@1 by up to 9.6x over inference-only and expert-iteration baselines.

Reasoning Over Mathematical Objects: On-Policy Reward Modeling and Test Time Aggregation

Reasoning Over Mathematical Objects: On-Policy Reward Modeling and Test Time Aggregation

Pranjal Aggarwal, Marjan Ghazvininejad, Seungone Kim, Ilia Kulikov, Jack Lanchantin, Xian Li, Tianjian Li, Bo Liu, Graham Neubig, Anaelia Ovalle, Swarnadeep Saha, Sainbayar Sukhbaatar, Sean Welleck, Jason Weston, Chenxi Whitehouse, Adina Williams, Jing Xu, Ping Yu, Weizhe Yuan, Jingyu Zhang, Wenting Zhao

arXiv2026

The ability to precisely derive mathematical objects is a core requirement for downstream STEM applications, including mathematics, physics, and chemistry. Yet, current LM evaluations of mathematical and scientific reasoning rely heavily on simplified answer formats. In this paper we provide three contributions: (i) we build and release training data and benchmarks for deriving mathematical objects, the Principia suite; (ii) we provide training recipes with strong LLM-judges and verifiers, where we show that on-policy judge training boosts performance; (iii) we show how on-policy training can also be used to scale test-time compute via aggregation. We find that strong LMs such as Qwen3-235B and o3 struggle on Principia, while our training recipes can bring significant improvements over different LLM backbones.

Verus-SpecGym: An Agentic Environment for Evaluating Specification Autoformalization

Verus-SpecGym: An Agentic Environment for Evaluating Specification Autoformalization

Anmol Agarwal, Natalie Neamtu, Pranjal Aggarwal, Seungone Kim, Jannis Limperg, Cedric Flamant, Kanna Shimizu, Bryan Parno, Sean Welleck

arXiv2026

We study whether LLM agents can translate informal programming problems into faithful formal specifications. We introduce Verus-SpecBench, 581 spec-writing tasks derived from Codeforces problems for the Verus verifier for Rust, and Verus-SpecGym, an agentic environment in which models write these specs. Generated specs are executed and tested against official Codeforces tests and adversarial hacks. The strongest model solves 77.8% of tasks, and LLM-as-a-judge evaluation misses 26% of the failures our evaluator catches.

On the Limits and Opportunities of AI Reviewers: Reviewing the Reviews of Nature-Family Papers with 45 Expert Scientists

On the Limits and Opportunities of AI Reviewers: Reviewing the Reviews of Nature-Family Papers with 45 Expert Scientists

Seungone Kim, Dongkeun Yoon, Kiril Gashteovski, Juyoung Suk, Jinheon Baek, Pranjal Aggarwal, et al.

arXiv2026

In a large expert annotation study, 45 scientists spent 469 hours rating 2,960 criticisms from human and AI reviews of 82 Nature-family papers on correctness, significance, and sufficiency of evidence. A reviewing agent powered by GPT-5.2 scores above each paper's top-rated human reviewer on a composite of all three, and AI reviewers raise 26% of issues that no human raises. However, AI reviewers overlap with each other far more than humans do and show 16 recurring weaknesses, so they are complements to, not substitutes for, human reviewers.

RLHF Deciphered: A Critical Analysis of Reinforcement Learning from Human Feedback for LLMs

RLHF Deciphered: A Critical Analysis of Reinforcement Learning from Human Feedback for LLMs

Shreyas Chaudhari*, Pranjal Aggarwal*, Vishvak Murahari, Tanmay Rajpurohit, Ashwin Kalyan, Karthik Narasimhan, Ameet Deshpande, Bruno Castro da Silva

ACM Computing Surveys2026

This paper analyzes RLHF through the lens of reinforcement learning principles to develop an understanding of its fundamentals, dedicating substantial focus to the core component -- the reward model. We characterize limitations including incorrect generalization, model misspecification, and sparsity of feedback. We provide a comprehensive survey covering reward model training, policy optimization, and emerging approaches, offering a unified framework for understanding the rapidly evolving RLHF landscape.

2025

L1: Controlling How Long A Reasoning Model Thinks With Reinforcement Learning

L1: Controlling How Long A Reasoning Model Thinks With Reinforcement Learning

Pranjal Aggarwal, Sean Welleck

COLM2025

We present L1, a method for controlling the inference-time compute of reasoning models through reinforcement learning. L1 enables models to adaptively allocate thinking time based on problem difficulty, improving efficiency without sacrificing accuracy.

AlphaVerus: Bootstrapping Formally Verified Code Generation through Self-Improving Translation and Treefinement

AlphaVerus: Bootstrapping Formally Verified Code Generation through Self-Improving Translation and Treefinement

Pranjal Aggarwal, Bryan Parno, Sean Welleck

ICML2025Best Theme Track Paper, LTI SRS 2025Oral, VerifAI@ICLR 2025

We introduce AlphaVerus, a system that bootstraps formally verified code generation through iterative self-improvement. AlphaVerus combines translation from natural language to verified code with tree-based refinement strategies.

Agentic-R1: Distilled Dual-Strategy Reasoning

Agentic-R1: Distilled Dual-Strategy Reasoning

Weihua Du, Pranjal Aggarwal, Sean Welleck, Yiming Yang

EMNLP2025

Current long chain-of-thought (long-CoT) models excel at mathematical reasoning but rely on slow and error-prone natural language traces. Tool-augmented agents address arithmetic via code execution, but often falter on complex logical tasks. We introduce DualDistill, a fine-tuning framework that distills complementary reasoning strategies from multiple teachers into a unified student model. Using this approach, we train Agentic-R1, which dynamically selects the optimal strategy for each query, invoking tools for arithmetic and algorithmic problems, and using text-based reasoning for abstract ones.

The Majority is not always right: RL training for solution aggregation

The Majority is not always right: RL training for solution aggregation

Wenting Zhao, Pranjal Aggarwal, Swarnadeep Saha, Asli Celikyilmaz, Jason Weston, Ilia Kulikov

arXiv2025

We propose to learn aggregation as an explicit reasoning skill: given a set of candidate solutions, we train an aggregator model to review, reconcile, and synthesize a final, correct answer using reinforcement learning from verifiable rewards. A key ingredient is careful balancing of easy and hard training examples. Empirically, our method AggLM outperforms both strong rule-based and reward-model baselines across multiple benchmarks, and generalizes effectively to solutions from differing models.

2024

AutoMix: Automatically Mixing Language Models

AutoMix: Automatically Mixing Language Models

Pranjal Aggarwal*, Aman Madaan*, Ankit Anand, Srividya Pranavi Potharaju, Swaroop Mishra, Pei Zhou, Aditya Gupta, Dheeraj Rajagopal, Karthik Kappaganthu, Yiming Yang, Shyam Upadhyay, Mausam, Manaal Faruqui

NeurIPS2024

Large language models (LLMs) are now available from cloud API providers in various sizes and configurations. We present AutoMix, an approach that strategically routes queries to larger LMs based on the approximate correctness of outputs from a smaller LM. AutoMix employs a few-shot self-verification mechanism and a POMDP-based router, reducing computational cost by over 50% for comparable performance.

GEO: Generative Engine Optimization

GEO: Generative Engine Optimization

Pranjal Aggarwal, Vishvak Murahari, Tanmay Rajpurohit, Ashwin Kalyan, Karthik Narasimhan, Ameet Deshpande

KDD2024

The advent of large language models has ushered in a new paradigm of search engines that use generative models to gather and summarize information. We introduce Generative Engine Optimization (GEO), the first novel paradigm to aid content creators in improving their content visibility in generative engine responses. GEO can boost visibility by up to 40%.

2023

Let's Sample Step by Step: Adaptive-Consistency for Efficient Reasoning and Coding with LLMs

Let's Sample Step by Step: Adaptive-Consistency for Efficient Reasoning and Coding with LLMs

Pranjal Aggarwal, Aman Madaan, Yiming Yang, Mausam

EMNLP2023Oral

We introduce Adaptive-Consistency, a method that dynamically adjusts the number of samples based on the model's confidence, significantly reducing computational costs while maintaining accuracy for reasoning and coding tasks.

SemSup-XC: Semantic Supervision for Zero and Few-Shot Extreme Classification

SemSup-XC: Semantic Supervision for Zero and Few-Shot Extreme Classification

Pranjal Aggarwal, Ameet Deshpande, Karthik Narasimhan

ICML2023

We introduce SemSup-XC, a method that leverages semantic supervision for zero and few-shot extreme classification. Our approach significantly outperforms existing baselines by utilizing rich semantic representations of labels.

Deep Learning for Detection of Iso-Dense, Obscure Masses in Mammographically Dense Breasts

Deep Learning for Detection of Iso-Dense, Obscure Masses in Mammographically Dense Breasts

Pranjal Aggarwal*, Krithika Rangarajan*, Dhruv Kumar Gupta, Rohan Raju Dhanakshirur, Akhil Baby, Chandan Pal, Arunkumar Gupta, Smriti Hari, Subhashis Banerjee, Chetan Arora

European Radiology2023

We present a deep learning model for improving cancer detection in mammographically dense breasts. Our three-pronged approach explicitly trains the network to recognize features like spiculations and architectural distortion, utilizes opposite breast comparison for asymmetry detection, and enhances images through piecewise-linear transformation. Results show sensitivity improvements across multiple datasets, with isodense/obscure cancer detection improving from 74.6% to 85.3%.