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Sourav Chakraborty
Ph.D. Candidate · Theoretical Machine Learning · University of Colorado
"All models are wrong, but some are useful." – George Box
[Name pronounced either as Saw-rv or Show-oo-rob (Bengali)]
I am a Ph.D. candidate at the University of Colorado Boulder, advised by Prof. Lijun Chen. I am working as a Graduate Research Assistant in the Department of Computer Science.
I am on the job market for Fall 2026.
My research focuses on the mathematical foundations of sequential decision-making under uncertainty, with a primary emphasis on Multi-Agent Reinforcement Learning (MARL) and Multi-Armed Bandits. I investigate how structural, physical, and strategic constraints shape the limits of learnability, particularly in decentralized coordination, continuous action spaces, and evolving networked structures.
Prior to my Ph.D., I earned my Master’s in Computer Science at the University of Colorado Boulder and my bachelor's degree from the Birla Institute of Technology, Mesra. Before moving to the U.S., I worked as a Software Engineer at Flipkart in Bangalore, designing scalable search pipelines and centralized data recovery platforms.
Beyond research, I find myself drawn to cinema, literature, and music. Cricket has been a constant since childhood: I played for a local club at school, later for the Flipkart corporate team, and now follow the game closely as a spectator.
Fun Fact. My Erdős Number is 4 and Dijkstra Number is 5.
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Taken in Ouray, Colorado, known as "The Switzerland of America".
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Updates & News
- 2026-02: Defended PhD Proposal (Comprehensive) Exam!
- 2026-01: Paper accepted at AISTATS 2026! Tangier, Morocco.
- 2026-01: Two papers accepted at L4DC 2026!, Los Angeles, CA.
- 2025-09: Paper accepted at NeurIPS 2025 workshop ARLET!, San Diego, CA.
- 2025-07: Paper accepted at IEEE CDC 2025!, Rio De Janeiro, Brazil.
- 2024-12: Cleared the Computer Science PhD Prelims (Area) Exam!
- 2024-03: Continuing as a CS Department Lead TA for the AY 2024-25.
- 2024-01: My first paper got accepted at IEEE ACC 2024!, Toronto, Canada.
- 2023-08: Guest lectured for Fall 2023 Advanced ML course on Bandit models.
- 2023-03: Elected as the student representive for the CS Graduate Committee.
- 2023-03: Re-appointed as a CS Department Lead TA for the AY 2023-24.
- 2022-08: Started my PhD journey at the University of Colorado Boulder in CS!
- 2022-05: Graduated with Master of Science (MS) in Computer Science!
- 2022-04: Successfully defended Master's thesis! (link)
- 2022-02: Got offer for Ph.D from CS @ Colorado for Fall 2022!
- 2019-08: Started Master of Science in Computer Science at Colorado!
- 2016-12: Joined Flipkart as a Software Engineer in Bangalore, India.
- 2016-06: Bachelor's in Engineering (B.E.) completed from BIT Mesra.
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Awards & Honors
- 2026-04: Recepient of the Summer 2026 Research Fellowship from the CS department.
- 2026-04: Recepient of the Outstanding Research Paper Award from the CS department.
- 2026-01: Recepient of the Conference Travel Award for CDC in Rio de Janeiro, Brazil 2025.
- 2025-11: Recepient of the Graduate Research Assistant Fellowship for Spring 2026.
- 2025-04: Recepient of the Outstanding Teaching Assistant Award from the CS department.
- 2025-04: Recepient of the Outstanding Service Award from the CS department.
- 2024-04: Recepient of the Outstanding Research Paper Award from the CS department.
- 2024-04: Recepient of the Full Conference Travel Fellowship for ACC in Toronto, Canada 2024.
- 2024-04: Recepient of the CU research Expo research poster award for the annual year 2023-24.
- 2024-03: Recepient of the Publication Recognition Award for the annual year 2023-24.
- 2022-09: Recepient of the Early Career Development Fellowship from the CS department.
- 2022-05: Recepient of the Lloyd Botway Award for Outstanding Master's student for "recognizing
excellence in academics, teaching, research, and service among the graduating cohort."
- 2022-04: Recepient of the CU research Expo research poster award for the annual year 2021-22.
- 2022-04: Selected as a Lead Teaching Assistant (department lead) for CS @ CU for the annual year.
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Research
I develop the mathematical foundations of sequential decision-making to establish how structural, physical, and strategic constraints shape the limits of learnability in uncertain and stochastic environments.
My overarching research agenda focuses on three core areas:
(i) Scalable Multi-Agent Reinforcement Learning, where I develop theoretical frameworks to overcome the curse of dimensionality by exploiting policy-dependent locality;
(ii) Graph-Constrained & Dynamic Bandits, characterizing the limits of online learning when an agent's actions are restricted by evolving network topologies;
and (iii) Continuous & Incentivized Learning, designing sequential decision-making algorithms for Lipschitz-structured action spaces and environments with biased feedback.
* Equal contribution.
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Multi-Agent Lipschitz Bandits.
Sourav Chakraborty*, Amit Kiran Rege*, Claire Monteleoni, Lijun Chen
Accepted at International Conference of Artificial Intelligence and Statistics (AISTATS) 2026 in Tangier, Morocco.
arXiv (preprint)
We introduce a communication-free, modular protocol for decentralized multi-player bandits over continuous, Lipschitz-structured action spaces. Our approach decouples agent coordination from exploration, achieving near-optimal regret without horizon-dependent coordination costs.
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Flickering Multi-Armed Bandits.
Sourav Chakraborty*, Amit Kiran Rege*, Claire Monteleoni, Lijun Chen
Accepted at Learning for Dynamics & Control Conference (L4DC) 2026 in Los Angeles, California, United States. (Selected as an Oral Presentation; ~Top 10%)
arXiv (preprint)
We formalize a novel bandit framework where arm availability is constrained by local moves on evolving random graphs (Erdős–Rényi and Edge-Markovian). We design a two-phase algorithm utilizing lazy random walks to achieve near-optimal, sublinear regret under these non-stationary physical constraints.
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A Unified Framework for Locality in Scalable MARL.
Sourav Chakraborty*, Amit Kiran Rege*, Claire Monteleoni, Lijun Chen
Accepted at Learning for Dynamics & Control Conference (L4DC) 2026 in Los Angeles, California, United States.
arXiv (preprint)
We establish that locality in decentralized MARL is inherently policy-dependent, introducing a novel spectral condition that decouples environmental coupling from policy smoothness. This framework enables policy improvement that circumvents the curse of dimensionality.
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Bandit Learning on Dynamic Graphs.
Sourav Chakraborty*, Amit Kiran Rege*, Claire Monteleoni, Lijun Chen
Accepted at ARLET Workshop at Neural Information Processing Systems (NeurIPS) 2025 in San Diego, California, United States.
OpenReview
We study online learning where an agent is constrained to local movements on a dynamic graph sequence.
We formalizing sufficient structural conditions for learnability and design near-optimal, exploration policies.
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Incentivized Lipschitz Bandits.
Sourav Chakraborty*, Amit Kiran Rege*, Claire Monteleoni, Lijun Chen
Accepted at IEEE Conference on Decision and Control (CDC) 2025 in Rio de Janeiro, Brazil.
IEEE /
arXiv
We develop incentivized exploration schemes in continuous metric spaces where the system compensates myopic agents to explore, despite receiving biased feedback. We develop near-optimal uniform discretization-based algorithms.
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Incentivized Exploration in Non-stationary Stochastic Bandits.
Sourav Chakraborty and Lijun Chen.
Accepted at IEEE American Control Conference (ACC) 2024 in Toronto, Canada.
Master's Thesis, Committee: Lijun Chen,
Raf Frongillo, Bo Waggoner.
IEEE version /
arXiv /
thesis
We address the challenge of incentivizing myopic agents to explore in both abruptly-changing and continuously-drifting bandit environments with drifted feedback and propose near-optimal algorithms.
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Work Experience
I worked on production systems at Flipkart across storage/reliability infrastructure and search relevance, with a focus on product discovery, ranking, and data reliability.
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Software Engineer at Flipkart (2016-2019)
- Built an end-to-end query suggestion pipeline (related search) for search and shopping intents, improving how users discover relevant products while typing.
- Developed and integrated ranking signals to improve retrieval quality and relevance ordering in the search experience.
- Built a pluggable backup platform (MySQL drivers) that evolved into BRaaS, a centralized backup/recovery service used across multiple Flipkart applications.
- Collaborated across infrastructure and product-search teams on cross-functional engineering efforts spanning discovery quality and system reliability.
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Teaching
My teaching contributions span undergraduate computer science instruction and department-level instructional support, including course operations, student-facing instruction, assessment, staff training, and mentorship.
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- Instructor of Record
- CSCI 1200: Introduction to Computational Thinking (Fall 2021)
- CSCI 3022: Introduction to Data Science with Probability & Statistics (Summer 2020)
- Primary instructor responsible for end-to-end course delivery (lecture planning, instruction, assessments, and final grading), including coordination of instructional staff; enrollments were ~200 and ~50, respectively.
- CS Department Lead Teaching Assistant (2022 - 2025)
- Selected by the department via teaching-performance review and interviews to support department-wide instructional quality.
- Helped conduct TA hiring interviews and ran annual onboarding/training for new TAs, graders, and instructional staff.
- Organized recurring workshops, mentored graduate TAs, and served as a liaison to communicate TA concerns to department leadership.
- Graduate Teaching Assistant (2020 - 2025)
- Algorithms (CSCI 3104), Data Structures (CSCI 2270/2275), and Starting Computing (CSCI 1300), across 10+ semesters.
- Responsibilities included weekly recitations, office hours, quizzes/lab facilitation, and assignment/exam grading.
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Last updated: April 2026 Thanks Jon Barron!
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