Vignesh Viswanathan

I am a Computer Science PhD candidate at the University of Massachusetts Amherst, where I am advised by Yair Zick. Prior to joining UMass Amherst, I received my undergraduate degree at IIT Kharagpur.

I like working on combinatorial problems in computational economics. My current focus is on problems in fair allocation and two sided matching. I have also worked on graph arrangements, market equilibria and explainable AI during my PhD.

During my PhD, I have been fortunate to intern at Microsoft Research (Summer 2022) and Adobe Research (Summer 2024). I have also had the pleasure of visiting Rohit Vaish at IIT Delhi (Winter 2024) and Siddharth Barman at IISc Bangalore (Winter 2025).

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Publications

Unless otherwise mentioned, authors are alphabetically ordered. For papers where authors are ordered by contribution, * is used to denote the lead author(s).

[W4]Equitable Colorings of Vertex Weighted Graphs
Siddharth Barman, Vignesh Viswanathan
Working Paper, 2026
arXiv /
tldr

We study equitable colorings of vertex-weighted graphs, where the goal is to find a proper coloring in which the color classes have approximately equal total weight.

[W3]Some Improved Results on Fair and Balanced Graph Partitions
Vignesh Viswanathan
Working Paper, 2026
arXiv /
tldr

Improved algorithms and approximation bounds for partitioning a graph into fair and balanced parts.

[W2]Best of Both Worlds Guarantees with Fairer Endings
Telikepalli Kavitha, Surya Panchapakesan, Rohit Vaish, Vignesh Viswanathan, Jatin Yadav
Working Paper, 2026
arXiv /
tldr

The paper studies the best-of-both-worlds framework for fair allocation of indivisible goods, with a focus on stronger ex-post guarantees.

[W1]Stable Matching under Matroid Rank Valuations
Alon Eden, Vignesh Viswanathan, Yair Zick
Working Paper, 2026
arXiv /
tldr

The paper studies two sided matching where one side has matroid rank valuations and the other side has unit demand valuations.

[C14]Improved Hardness Results for Nash Social Welfare, Budgeted Allocation and GAP via the Unique Games Conjecture
Vignesh Viswanathan
EC, 2026
arXiv /
tldr

A new dictator test for allocation problems with applications to Nash welfare, budgeted allocation and GAP.

[J3]A General Framework For Fair Allocation under Matroid Rank Valuations
Vignesh Viswanathan, Yair Zick
Transactions on Economics and Computation, 2025
link /
tldr

A framework that implies efficient algorithms for almost all fairness objectives when agents have binary submodular valuations. Subsumes our AAMAS 2023 and EC 2023 papers.

[C13]On the Hardness of Fair Allocation under Ternary Valuations
Zack Fitzsimmons, Vignesh Viswanathan, Yair Zick
AAMAS, 2025
arXiv /
tldr

Hardness results for fair allocation under ternary valuations. We also prove an important result about order neutral submodular valuations, generalizing a result from our WINE 2023 paper.

[C12]Towards Optimal Multi-draft Speculative Decoding
Zhengmian Hu*, Tong Zheng, Vignesh Viswanathan, Ziyi Chen, Ryan A. Rossi, Yihan Wu, Dinesh Manocha, Heng Huang
ICLR, 2025
arXiv /
tldr

Improved results on multi-draft speculative decoding. This paper contains a surprising connection between multi-draft speculative decoding and total unimodularity.

[J2]Graphical House Allocation with Identical Valuations
Hadi Hosseini, Andrew McGregor, Justin Payan, Rik Sengupta, Rohit Vaish, Vignesh Viswanathan
Journal of Autonomous Agents and Multi-agent Systems, 2024
link /
tldr

How to assign a set of numbers to the vertices of a graph so as to minimize the sum of absolute differences along the edges? Subsumes our AAMAS 2023 paper.

[J1]Simple Steps to Success: A Method for Step-Based Counterfactual Explanations
Jenny Hamer, Nicholas Perello, Jake Valladares, Vignesh Viswanathan, Yair Zick
Transactions of Machine Learning Research, 2024
link /
tldr

A new method to generate counterfactual explanations for machine learning models.

[C11]Tight Approximations for Graphical House Allocation
Hadi Hosseini, Andrew McGregor, Rik Sengupta, Rohit Vaish, Vignesh Viswanathan
AAMAS, 2024
arXiv /
tldr

Approximation algorithms for the graphical house allocation problem studied in our AAMAS 2023 paper. Also, Ramanujan graphs and a cool connection between graph cuts and bitstrings.

[C10]Axiomatic Aggregations of Abductive Explanations
Gagan Biradar, Yacine Izza, Elita Lobo, Vignesh Viswanathan, Yair Zick
AAAI, 2024
arXiv /
tldr

Cooperative game theory meets formal logic meets model explanations!

[O1]The Theory of Fair Allocation Under Structured Set Constraints
Arpita Biswas, Justin Payan, Rik Sengupta, Vignesh Viswanathan
Book Chapter in Ethics in Artificial Intelligence: Bias, Fairness and Beyond (Springer), 2023
link /
tldr

Thanks to Arpita, I got to be co-author of a book chapter!

[C9]The Good, the Bad and the Submodular: Fairly Allocating Mixed Manna Under Order-Neutral Submodular Preferences
Cyrus Cousins, Vignesh Viswanathan, Yair Zick
WINE, 2023
arXiv /
tldr

Fair allocation of indivisible items when agents valuations are submodular and each item has a marginal contribution of -1, 0 or some positive integer c.

[C8]Dividing Good and Great Items Among Agents with Bivalued Submodular Valuations
Cyrus Cousins, Vignesh Viswanathan, Yair Zick
WINE, 2023
arXiv /
tldr

Algorithms for fair allocation of indivisible items when agents valuations are submodular and each item has a marginal contribution of 1 or some positive integer c.

[C7]A General Framework For Fair Allocation with Matroid Rank Valuations
Vignesh Viswanathan, Yair Zick
EC, 2023
arXiv /
tldr

A framework that implies efficient algorithms for almost all fairness objectives when agents have binary submodular valuations. Superseded by our TEAC 2025 paper.

[C6]Yankee Swap: A Fast and Simple Fair Allocation Mechanism for Matroid Rank Valuations
Vignesh Viswanathan, Yair Zick
AAMAS, 2023
arXiv /
tldr

A fast algorithm to compute leximin allocations when agents have binary submodular valuations. Superseded by our TEAC 2025 paper.

[C5]Graphical House Allocation
Hadi Hosseini, Justin Payan, Rik Sengupta, Rohit Vaish, Vignesh Viswanathan
AAMAS, 2023
arXiv /
tldr

How to assign a set of numbers to the vertices of a graph so as to minimize the sum of absolute differences along the edges? Superseded by our JAAMAS 2024 paper.

[C4]Relaxations of Envy-Freeness Over Graphs
Justin Payan, Rik Sengupta, Vignesh Viswanathan
AAMAS, 2023 (Extended Abstract)
arXiv / Code /
tldr

Can we compute allocations that satisfy the envy-free up to any good (EFX) condition only for certain pairs of agents?

[C3]Moving Target Defense under Uncertainty for Web Applications
Vignesh Viswanathan*, Megha Bose*, Praveen Paruchuri
AAMAS, 2022 (Extended Abstract)
arXiv / Code /
tldr

Can we hide the vulnerabilities of a web application by randomizing over multiple implementations?

[C2]The Price is (Probably) Right: Learning Market Equilibria From Samples
Neel Patel, Omer Lev, Vignesh Viswanathan, Yair Zick
AAMAS, 2021
arXiv / Code /
tldr

Algorithms to compute approximate market equilibria when the only knowledge of agent preferences comes from samples.

[C1]Fighting Wildfires under Uncertainty: A Sequential Resource Allocation Approach
Hau Chan, Long Tran-Thanh, Vignesh Viswanathan
IJCAI, 2020
Paper /
tldr

Allocating scarce firefighting resources to different regions under uncertainty.


Thanks and Thanks!