Hanlin Ren
Photo taken by Rahul Ilango
I am a postdoctoral member at the School of Mathematics, Institute for Advanced Study. Previously, I was a DPhil student at the University of Oxford, very fortunately advised by Prof. Rahul Santhanam. I was a member of Christ Church and also a Clarendon scholar. Before that, I was an undergraduate student at Institute for Interdisciplinary Information Sciences, Tsinghua University.
I have a broad interest in theoretical computer science. Currently, I am interested in computational complexity, which studies the limitations of efficient computation. Some topics of complexity theory that I find fascinating are circuit complexity, proof complexity, meta-complexity, explicit constructions, and average-case complexity.
At Tsinghua, I was advised by Prof. Ran Duan and worked on graph algorithms. One emphasis of my research was to design shortest-path data structures for graphs in the presence of failures.
[Google Scholar], [DBLP], [Twitter], [ORCID]
Contact:
- h4n1in {DOT} r3n <AT> gmail {DOT} com. (recommended)
- h {DOT} ren <AT> ias {DOT} edu.
News
Mar 2026: Slides, first part, second part of my talk on reverse mathematics of complexity lower bounds at IAS CSDM Seminar.
Sep 2025: Very excited to join the IAS!
Feb 2024: I'm visiting Shuichi Hirahara in 2024 Spring!
Jan 2023: I'm visiting Lijie Chen and the Meta-Complexity program at Simons Institute in 2023 Spring.
Selected Papers
(In theoretical computer science, the list of authors are usually sorted in alphabetical order.)
Finding Bugs in Short Proofs: The Metamathematics of Resolution Lower Bounds, with Jiawei Li and Yuhao Li
[ECCC], [arXiv], [Slides at SJTU (gentle intro)], [Slides at Oxford proof complexity workshop (slightly more bounded arithmetic)], [Summary]
In ACM Symposium on Theory of Computing (STOC) 2026
Hardness of Range Avoidance and Proof Complexity Generators from Demi-Bits, with Yichuan Wang and Yan Zhong
[ECCC], [arXiv], [eprint], [Independent and concurrent work by Rahul Ilango], [Slides at Prague Logic Seminar (proof complexity oriented)], [Slides and video at Princeton Theory Lunch (focused on "cryptography against nondeterministic adversaries")], [Summary]
In Innovations in Theoretical Computer Science (ITCS) 2026, Best Student Paper Award
Polynomial-Time Pseudodeterministic Construction of Primes, with Lijie Chen, Zhenjian Lu, Igor C. Oliveira, and Rahul Santhanam
[ECCC], [arXiv], [JACM], [Twitter], [Slides at UIUC Theory Seminar], [Slides and video at TCS+], [Slides and video at explicit construction workshop], [Slides (first half) and video at IAS], [Summary]
In Journal of the ACM; preliminary version in FOCS 2023
On the Range Avoidance Problem for Circuits, with Rahul Santhanam and Zhikun Wang
[ECCC], [Twitter], [Poster at Oxford Computer Science Conference], [Slides and video at ICMS (focused on proof complexity)], [Slides at Complexity Meetings], [Summary]
In IEEE Symposium on Foundations of Computer Science (FOCS) 2022