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), working with Prof. Katya Scheinberg. My research interests are primarily in optimization, with twin interests in theoretical foundations and computational practice, particularly in large-scale and limited-information settings.

For students: I am always interested in working with motivated students. Northwestern students and prospective PhD applicants are welcome to contact me.

Curriculum Vitae (CV) Google Scholar

Research Overview

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My research to date has focused on developing, understanding, and enhancing optimization algorithms, particularly in large-scale and limited-information settings -- both generically and in specific applications. A recurring goal in my work is to uncover structural insights into algorithmic behavior that inform both theory and computational practice. I am delighted that some of my methods have already been implemented in state-of-the-art commercial optimization solvers. My work has received second place in the George B. Dantzig Dissertation Award, won the INFORMS Optimization Society Student Paper Prize, and been a finalist in the George Nicholson Student Paper Competition. My overarching aspiration is to broaden the capabilities of modern optimization methods to effectively solve problems arising in operations research, data science, and machine learning/AI.

News

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September 2026 My sole-authored paper, High-Probability Polynomial-Time Complexity of Restarted PDHG for Linear Programming, was accepted for publication in Mathematics of Operations Research.
August 2026 My new paper with Robert Freund, Symmetry-dependence in Rounding of a Convex Body, is now available on arXiv.
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

Selected Recent Research

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(alphabetical authorship marked with *)

My last name, Xiong (熊), means “bear” in Chinese — hence the little bear in your browser tab.

I am lucky to share this academic life with my partner, Kamessi Zhao.