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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profile photo

Taken in Ouray, Colorado,
known as "The Switzerland of America".

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.
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.
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.

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.
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.
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.
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.
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.
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.

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.

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.
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.

  • 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.

Last updated: Feb 2026
Thanks Jon Barron!