Xuandi Ren

Research

  • As an undergraduate, I collaborated with Prof. Bingkai Lin on Parameterized Inapproximability, with Prof. Huacheng Yu on Sketching Complexity, and with Prof. Pinyan Lu on Algorithms with Predictions.

  • During my Ph.D., my research has focused primarily on Hardness of Approximation.

  • More recently, I have become interested in exploring large language models. From June 2025 to August 2026, I was interning at ByteDance Seed as a student researcher.

Publications

(Unless stated otherwise, authors are sorted in alphabetical order)

  • Inapproximability of Unique-Machine Precedence Scheduling for Unit-Length Jobs.
    Venkatesan Guruswami, Xuandi Ren, Shaoxuan Tang.
    Preprint. [arxiv]

  • On the Approximability of Parameterized Minimum Monotone Satisfying Assignment.
    Venkatesan Guruswami, Bingkai Lin, Xuandi Ren, Xin Zheng.
    In APPROX 2026. [arxiv]

  • Strong Inapproximability for a Promise Rank Problem.
    Venkatesan Guruswami, Xuandi Ren, Shaoxuan Tang.
    In APPROX 2026. [arxiv]

  • Brief Announcement: Scheduling Problems with Constrained Rejections.
    Sami Davies, Venkatesan Guruswami, Xuandi Ren.
    In SPAA 2026. [arxiv]

  • On Inapproximability of Reconfiguration Problems: PSPACE-Hardness and some Tight NP-Hardness Results.
    Venkatesan Guruswami, Karthik C. S., Pasin Manurangsi, Xuandi Ren, Kewen Wu.
    Preprint. [arxiv] (Merged from [KM24] and [GRW25])

  • Inapproximability of Finding Sparse Vectors in Codes, Subspaces, and Lattices.
    Vijay Bhattiprolu, Venkatesan Guruswami, Euiwoong Lee, Xuandi Ren.
    In FOCS 2025. [arxiv]

  • Almost Optimal Time Lower Bound for Approximating Parameterized Clique, CSP, and More, under ETH.
    Venkatesan Guruswami, Bingkai Lin, Xuandi Ren, Yican Sun, Kewen Wu.
    In STOC 2025. [arxiv] [slides]

  • Baby PIH: Parameterized Inapproximability of Min CSP.
    Venkatesan Guruswami, Xuandi Ren, Sai Sandeep.
    In CCC 2024. [arxiv] [slides]

  • Parameterized Inapproximability Hypothesis under ETH.
    Venkatesan Guruswami, Bingkai Lin, Xuandi Ren, Yican Sun, Kewen Wu.
    In STOC 2024 (Best Paper Award) and Journal of the ACM, Vol. 72, No. 5. [arxiv] [journal] [slides]

  • Improved Hardness of Approximating k-Clique under ETH.
    Bingkai Lin, Xuandi Ren, Yican Sun, Xiuhan Wang.
    In FOCS 2023. [arxiv] [slides]

  • Constant Approximating Parameterized k-SetCover is W[2]-hard.
    Bingkai Lin, Xuandi Ren, Yican Sun, Xiuhan Wang.
    In SODA 2023. [arxiv] [slides]

  • On Lower Bounds of Approximating Parameterized k-Clique.
    Bingkai Lin, Xuandi Ren, Yican Sun, Xiuhan Wang.
    In ICALP 2022. [arxiv] [slides]

  • Generalized Sorting with Predictions.
    Pinyan Lu, Xuandi Ren, Enze Sun, Yubo Zhang.
    In SOSA 2021. [arxiv] [slides]