Zikai Xiong

I am a tenure-track Assistant Professor at Northwestern IEMS.

I am a tenure-track Assistant Professor in the Northwestern University Department of Industrial Engineering and Management Sciences (IEMS). I received my Ph.D. from the MIT Operations Research Center (ORC), advised by Prof. Robert Freund. Before joining Northwestern, I spent a year as a postdoctoral fellow at the Georgia Tech H. Milton Stewart School of Industrial and Systems Engineering (ISyE) and the Algorithms and Randomness Center (ARC), working with Prof. Katya Scheinberg. My current research interests are mainly in optimization, with twin interests in theoretical foundations and computational practice.

For students: I work with a small number of motivated students each year. Northwestern students are welcome to contact me. If you are not yet a Northwestern student and hope to pursue a PhD working with me, please apply to the Northwestern IEMS PhD program. You are also welcome to email a brief note about yourself. I do my best to read all messages, though I may not be able to respond to each one.

Curriculum Vitae (CV) Google Scholar

Research Overview

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My research up to now has involved enhancing the scalability of optimization algorithms for solving large-scale linear and convex optimization -- both generically as well as on specific applications. I am delighted that some of my methods have already been implemented in the state-of-the-art commercial solvers. My work received second place in the George B. Dantzig Dissertation Award, won the INFORMS Optimization Society Student Paper Prize, and was a finalist in the George Nicholson Student Paper Competition. My overarching aspiration is to extend the capability of modern optimization methods to effectively solve problems arising in operations research, data science, and machine learning/AI.

News

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July 2026 I started my new position as a tenure-track Assistant Professor at Northwestern IEMS.
June 2026 My sole-authored paper, Accessible Complexity Bounds for Restarted PDHG on Linear Programs with a Unique Optimizer, was accepted for publication in Mathematics of Operations Research.
June 2026 I presented a talk at the Third Derivative-Free Optimization Symposium (DFO26)
Function-Free Optimization via Comparison Oracles
June 2026 I presented a talk at the SIAM Conference on Optimization (OP26)
Function-Free Optimization via Comparison Oracles
Apr 2026 My new paper with Katya Scheinberg, Function-Free Optimization via Comparison Oracles, is now available on arXiv.

Selected Papers

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(alphabetical authorship marked with *)