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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, working as a Graduate Research Assistant in the Department of Computer Science. I am advised by Prof. Lijun Chen.
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.
I am currently on the job market for Fall 2026.
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/
slides)
- 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
- 2026-01: 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.
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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)
Abstract (short): 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)
Abstract (short): 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)
Abstract (short): 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.
arXiv
Abstract (short): 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
Abstract (short): 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
Abstract (short): 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
- 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: Feb 2026 Thanks Jon Barron!
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