Linus Richter

MeI am a Research Fellow in the Department of Mathematics at the National University of Singapore. My research interests lie in both computability theory and set theory, and especially at their intersection. Currently, I am working on questions in descriptive set theory, (algorithmic and computational) complexity theory, and automata theory.

Previously, I completed a PhD in mathematics at Victoria University of Wellington (NZ) advised by Dan Turetsky. Before coming to New Zealand, I received a Master’s degree from the University of Manchester (UK) in 2018. My Master’s thesis was supervised by Gareth Jones.

Contact: richter@nus.edu.sg

Research Papers

Co-analytic Counterexamples to Marstrand’s Projection Theorem[ arXiv / PDF ]
Submitted for publication
More on Bases of Uncountable Free Abelian Groups [ PDF ]
with Noam Greenberg, Saharon Shelah, and Dan Turetsky
To appear

Theses

On the Definability and Complexity of Sets and Structures [ PDF ]
PhD thesis 2024
Topics in Set Theory and Logic [ PDF ]
Master’s thesis 2018

Talks

The Borel-Definable Group Cohomology of ℝn Is (Hopefully) Simple [ PDF ]
IMS Graduate Summer School in Logic, National University of Singapore Jun 2023
On CA-Recursion and Marstrand’s Theorem
Victoria University of Wellington Logic Seminar Mar 2023
Pt 1: Controlling the Construction of CA-sets [ PDF ]
Pt 2: CA Counterexamples to Marstrand’s Projection Theorem [ PDF ]
Co-analytic Counterexamples to Marstrand’s Projection Theorem
Penn State Logic Seminar // online Sep 2023 [ PDF ]
National University of Singapore Logic Seminar // online Mar 2023 [ PDF ]
Computability Theory and Applications Seminar // online Jan 2023 [ PDF ]
On (Borel) Group Extensions
University of Sydney Graduate Talks in Topology and Geometry (GT)2 // online
May 2022 [ PDF Slides / PDF Handwritten ]
On Homological Algebra, Group Extensions, and Descriptive Set Theory [ PDF ]
Victoria University of Wellington SMS Graduate Seminar May 2021
When the Search for Proofs Turns Futile [ PDF ]
Victoria University of Wellington SMS Graduate Seminar Nov 2020
Higher Derived Limits and Cohomology of Ordinals [ PDF ]
Victoria University of Wellington Logic Seminar Apr 2020
Computability, Complexity, and Some Algebra [ PDF ]
NZMASP 2019, Wainui Nov 2019
More on Bases of Uncountable Free Abelian Groups
Victoria University of Wellington Logic Seminar Aug 2019

Miscellaneous

Short Teaching Notes
ℝ3 is a union of disjoint circles, assuming AC [ PDF ]
One Way to Think About: Zorn’s Lemma [ PDF ]
One Way to Think About: Change of Basis Matrices [ PDF ]
Doctoral Proposal [ PDF ]
Victoria University of Wellington Mar 2020