Research

(alphabetical authorship marked with *)

PhD Dissertation

• New Theory and New Practical Methods for Solving Large-Scale Linear and Conic Optimization PhD Dissertation link ⭐ Second Place, 2025 George B. Dantzig Dissertation Award

Journal Papers and Preprints

• Function-Free Optimization via Comparison Oracles Katya Scheinberg* and Zikai Xiong* Under review paper talk recording
• A Practical GPU-Enhanced Matrix-Free Primal-Dual Method for Large-Scale Conic Programs Zhenwei Lin, Zikai Xiong, Dongdong Ge and Yinyu Ye Under review paper software (supports JuMP and CVXPY)
• Two Sides of "Hidden City Ticketing": Analysis of a Choice-Based Network Revenue Management Model Jiacheng Guo*, Bo Jiang*, Zikai Xiong*, and Nanxi Zhang* Under review paper
• High-Probability Polynomial-Time Complexity of Restarted PDHG for Linear Programming Zikai Xiong Under revision at Mathematics of Operations Research paper
• Accessible Complexity Bounds for Restarted PDHG on Linear Programs with a Unique Optimizer Zikai Xiong Under revision at Mathematics of Operations Research paper slides ⭐ Winner, 2025 INFORMS Optimization Society Student Paper Prize
• The Role of Level-Set Geometry on the Performance of PDHG for Conic Linear Optimization Zikai Xiong and Robert M. Freund Under revision for resubmission paper slides ⭐ Finalist, 2024 George Nicholson Student Paper Competition
• Computational Guarantees for Restarted PDHG for LP based on "Limiting Error Ratios" and LP Sharpness Zikai Xiong and Robert M. Freund Mathematical Programming, 2026 paper slides additional results ⭐ Honorable Mention, 2024 INFORMS Optimization Society Student Paper Prize
• From an Interior Point to a Corner Point: Smart Crossover Dongdong Ge*, Chengwenjian Wang*, Zikai Xiong*, and Yinyu Ye* INFORMS Journal on Computing, 2025 paper codes slides
• Using Taylor-Approximated Gradients to Improve the Frank-Wolfe Method for Empirical Risk Minimization Zikai Xiong and Robert M. Freund SIAM Journal on Optimization, 2024 paper slides additional results and extensions
• Low-rank Traffic Matrix Completion with Marginal Information Zikai Xiong, Renjie Xu, Yanwei Xu, and Yimin Wei Journal of Computational and Applied Mathematics, 2022 paper

Papers Published at Conferences

• Fair Wasserstein Coresets Zikai Xiong, Niccolò Dalmasso, Shubham Sharma, Freddy Lecue, Daniele Magazzeni, Vamsi K. Potluru, Tucker Balch, Manuela Veloso Preliminary version appeared in NeurIPS 2023 Workshop SyntheticData4ML (Oral Presentation) Neural Information Processing Systems (NeurIPS 2024) paper workshop version
• FairWASP: Fast and Optimal Fair Wasserstein Pre-processing Zikai Xiong, Niccolo Dalmasso, Alan Mishler, Vamsi Potluru, Tucker Balch, Manuela Veloso AAAI Conference on Artificial Intelligence (AAAI 2024) paper
• Learning from Multiple Annotator Noisy Labels via Sample-wise Label Fusion Zhengqi Gao, Fan-Keng Sun, Mingran Yang, Sucheng Ren, Zikai Xiong, et al. European Conference on Computer Vision (ECCV 2022) paper codes
• Interior-Point Methods Strike Back: Solving the Wasserstein Barycenter Problem Dongdong Ge*, Haoyue Wang*, Zikai Xiong*, and Yinyu Ye* Neural Information Processing Systems (NeurIPS 2020) paper codes slides

Technical Reports

• A Technical Note on the Implementation and Use of PDCS Zhenwei Lin, Zikai Xiong, Dongdong Ge, Yinyu Ye technical report
• On the Relation Between LP Sharpness and Limiting Error Ratio and Complexity Implications for Restarted PDHG Zikai Xiong and Robert M. Freund technical report

Patent Applications

• Method and System for Generating Fair Synthetic Representative Data via Optimal Transport Niccolò Dalmasso, Zikai Xiong, Vamsi Krishna Potluru, Tucker Richard Balch and Manuela Veloso U.S. Patent Application Publication No. US 2025/0181999 A1, pending, 2025. link
• Method and System for Pre-processing Data for Algorithmic Fairness via Optimal Transport Niccolò Dalmasso, Zikai Xiong, Alan Mishler, Vamsi Krishna Potluru, Tucker Richard Balch and Manuela Veloso U.S. Patent Application Publication No. US 2025/0173389 A1, pending, 2025. link