Sourav Chakraborty
Ph.D. Student · 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. student at the University of Colorado Boulder, working as a Graduate Research Assistant at 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, particularly, Multi-Armed Bandit models and Reinforcement Learning.

Prior to my Ph.D., I completed a Master’s in Computer Science at the University of Colorado Boulder. I earned my bachelor's degree from the Birla Institute of Technology, Mesra in Ranchi, India, and worked as a software engineer at Flipkart in Bangalore before moving to the United States.

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 and later for the Flipkart team, and now follow the game closely as a spectator.

Fun Fact. My Erdős Number is 4 and Djikstra Number is 5.


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profile photo

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

Updates & News
  • 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 investigate how structural, physical, and strategic constraints shape the limits of learnability in uncertain environments. My work focuses on three core pillars:

  • Graph-Constrained Bandits. Characterizing the anatomy of regret when actions are restricted to local moves on evolving graphs, and designing algorithms that balance statistical learning with physical navigation costs.
  • Scalable Multi-Agent Systems. Exploiting policy-dependent locality to overcome the curse of dimensionality in decentralized MARL, using spectral conditions to enable provably sound, communication-free learning at scale.
  • Incentivized Exploration. Creating mechanisms that compensate myopic agents to explore under non-stationary rewards and biased feedback, connecting online learning with incentive design.
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.
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%)
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.
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
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
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

Teaching
  • Fall 2025: Teaching Assistant for CSCI 2275 - Programming and Data Structures.
  • Summer 2025: Teaching Assistant for CSCI 1300 - Starting Computing
  • Spring 2025: Teaching Assistant for CSCI 3104 - Algorithms
  • Fall 2024: Teaching Assistant for CSCI 3104 - Algorithms
  • Summer 2024: Teaching Assistant for CSCI 2270 - Data Structures.
  • Spring 2024: Teaching Assistant for CSCI 3104 - Algorithms
  • Fall 2023: Teaching Assistant for CSCI 2275 - Programming and Data Structures.
  • Spring 2023: Teaching Assistant for CSCI 2270 - Data Structures.
  • Fall 2022: Teaching Assistant for CSCI 2270 - Data Structures.
  • Spring 2022: Teaching Assistant for CSCI 2270 - Data Structures.
  • Fall 2021: Instructor for CSCI 1200 - Introduction to Computational Thinking.
  • Summer 2021: Teaching Assistant for CSCI 1300 - Starting Computing.
  • Spring 2021: Teaching Assistant for CSCI 1300 - Starting Computing.
  • Fall 2020: Teaching Assistant for CSCI 1300 - Starting Computing.
  • Summer 2020: Instructor for CSCI 3022 - Introduction to Data Science with Probability & Statistics.
Work Experience
  • Built an end-to-end Searches and Shopping Ideas pipeline in Java Cascading that suggests contextually relevant queries, broadening what shoppers can discover as they type.
  • Designed learning-driven ranking signals that improved how relevant results surface across the search experience.
  • Built a pluggable backup platform with MySQL drivers that matured into BRaaS (Backup Recovery as a Service), the centralized service safeguarding and restoring data for every Flipkart application.
Selected Personal Projects

*Alphabetically

Inverse Reinforcement Learning via Maximum Entropy Formulation.
Tuhina Tripathi, Alexa Reed, Sourav Chakraborty
April , 2022
report  /  code /  demo /  interface-code

Final project for ASEN 5519: Decision Making Under Uncertainty. This project explores the use of Inverse Reinforcement Learning, via Maximum Entropy Formulation, in a Markov Decision Process. The concepts explored in this project were demonstrated using a grid world environment.

Incentivized Exploration for Multi-Armed Bandits under Reward Drift.
Sourav Chakraborty
September, 2020
original paper  /  code

Just playing around with the paper by Liu & Wang et alon Incentivized Exploration for Multi-Armed Bandits under Reward Drift where the players receive compensation for exploring arms other than the greedy choice and may provide biased feedback on reward drift.

Contextual vectorized representation of words: Soam word embeddings
*Amit Baran Roy, Sourav Chakraborty
May, 2020
report  /  code

A word embedding model implementation based on the popular skipgram architecture. It involves alterations of the scoring algorithm to give more weightage to the context words that are closer to the target word in a skipgram sliding window.

Solving Games using the combination of Q-learning and Regret Matching Methods
Sourav Chakraborty, Nagarajan Shanmuganathan
May, 2020
report  /  code

It is known well that Counterfactual regret minimization (CFR) has been used in games which have both terminal states and perfect recall to minimize regret. This project aims to relax those constraints and use a local no-regret algorithm (LONR) by Kash et al, which internally uses a Q-learning like update rule to games which do not have terminal states or perfect recall.

Occupancy Network based 3D Image Reconstruction using Single-Depth View
*Amit Baran Roy, Aparajita Singh, Sourav Chakraborty, Tanmai Gajula
Feb-April, 2020
report  /  code

The complete 3D geometry of an object from a single 2.5D depth view was acquired by using deep learning techniques such as generative adversarial networks and 3D convolution neural networks. The resolution of the final 3D voxelized output was improved by transforming the voxel representation into another representation called occupancy networks.

Last updated: Jan 2026
Thanks Jon Barron!