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.
Recent Papers
(In theoretical computer science, the list of authors are usually sorted in alphabetical order.)
Many Proof Complexity Generators Inside One Demi-Bits Generator, with Xin Li and Yan Zhong
[Summary]
To appear in IEEE Symposium on Foundations of Computer Science (FOCS) 2026
Near-Maximum Circuit Lower Bounds for Exponential Time with Merlin-Arthur Queries, with Ryan Williams
To appear in IEEE Symposium on Foundations of Computer Science (FOCS) 2026
The Weak Rank Principle: Lower Bounds and Applications, with Michal Garlík, Svyatoslav Gryaznov, and Iddo Tzameret
In ACM Symposium on Theory of Computing (STOC) 2026
Selected Papers
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