I am a Lecturer in the College of Science and Engineering at Flinders University in Adelaide, Australia. My research interests lie in both computability theory and set theory, and especially at their intersection, including:
- descriptive set theory
- algorithmic randomness
- interactions between computability theory and set theory
- formal language theory
Previously, I was a Research Fellow at the National University of Singapore, working with Sanjay Jain, Frank Stephan, and Yang Yue. Prior, I completed a PhD in mathematics at Victoria University of Wellington (New Zealand) advised by Dan Turetsky. Before going to New Zealand, I received a Master’s degree from the University of Manchester (United Kingdom) in 2018. My Master’s thesis was supervised by Gareth Jones.
Contact
Email: linus.richter (at) flinders (dot) edu (dot) au
Papers
- (with H. Fernau, S. Jain, F. Stephan, D. Turetsky) Non-terminal Complexity of Simple Semi-Conditional Grammars, submitted
∎ pdf
- (with F. Stephan, X. Zhang) Chains and Antichains Inside Many-One Degrees and Variants, submitted
∎ pdf
- Co-analytic Counterexamples to Marstrand's Projection Theorem, submitted
∎ pdf | ↗︎ arXiv
- (with J. Chen, B. Kjos-Hanssen, I. Koswara, F. Stephan) Languages of Words of Low Automatic Complexity Are Hard to Compute, FSTTCS 2025, 17-19 December, 2025, BITS Pilani, K K Birla Goa Campus, India
∎ pdf | ↗︎ arXiv
- (with N. Greenberg, S. Shelah, D. Turetsky) More on bases of uncountable free abelian groups, volume 44 of Lecture Notes Series, Institute for Mathematical Sciences, National University of Singapore, p. 71-85, World Scientific, 2025
∎ pdf | ↗︎ published version
- All Borel Group Extensions of Finite-Dimensional Real Space Are Trivial, preprint
∎ pdf | ↗︎ arXiv
Theses
- On the Definability and Complexity of Sets and Structures, PhD thesis, Victoria University of Wellington, 2024
∎ pdf | ↗︎ published version
- Topics in Set Theory and Logic, Master's thesis, University of Manchester, 2018
∎ pdf
- Constructible Failures of the Erdős-Volkmann-Problem for Rings, Computability and Complexity in Analysis, RIMS Kyoto, Japan, Sep 2025
∎ slides pdf
- Projective Pathways Towards Roitman's Model Hypothesis, Set Theory and Topology in Messina, Messina, Italy, Sep 2025
∎ slides pdf
- Building Structures From Reals, 2025 Fudan Conference on Mathematical Logic, Fudan University, Shanghai, China, Aug 2025
∎ slides pdf
- Regularity Properties in Fractal Geometry, Old and New, Logic Seminar, The University of Manchester, Jun 2025
∎ slides pdf
- Computability, Consistency, and a Theorem on Fractals, Logic, Categories and Applications Seminar, University of Bologna, Dec 2024
∎ slides pdf
- On the Definability and Complexity of Sets and Structures, Colloquium Logicum 2024, PhD Colloquium, Austrian Academy of Sciences, Oct 2024
∎ slides pdf
- The Borel-Definable Group Cohomology of ℝn Is (Hopefully) Simple, IMS Graduate Summer School in Logic, National University of Singapore, Jun 2023
∎ notes pdf
- On Π11-recursion and Marstrand's Theorem, Victoria University of Wellington Logic Seminar
- Controlling the Construction of CA-sets, Mar 2023, ∎ notes pdf
- CA Counterexamples to Marstrand's Projection Theorem, Mar 2023, ∎ notes pdf
- Co-analytic Counterexamples to Marstrand's Projection Theorem
- Penn State Logic Seminar, online, Sep 2023, ∎ slides pdf
- National University of Singapore Logic Seminar, online, Mar 2023, ∎ slides pdf
- Computability Theory and Applications Seminar, online, Jan 2023, ∎ slides pdf
- On (Borel) Group Extensions, University of Sydney Graduate Talks in Topology and Geometry (GT)^2, online, May 2022
∎ slides pdf | ∎ handwritten notes pdf
- On Homological Algebra, Group Extensions, and Descriptive Set Theory, Victoria University of Wellington SMS Graduate Seminar, May 2021
∎ notes pdf
- When the Search for Proofs Turns Futile, Victoria University of Wellington SMS Graduate Seminar, Nov 2020
∎ notes pdf
- Higher Derived Limits and Cohomology of Ordinals, Victoria University of Wellington Logic Seminar, Apr 2020
∎ notes pdf
- Computability, Complexity, and Some Algebra, NZMASP, Wainui, Nov 2019
∎ slides pdf
- More on Bases of Uncountable Free Abelian Groups, Victoria University of Wellington Logic Seminar, Aug 2019
Below I include a few short notes I have written as additional teaching materials to students during my teaching. I include them in the hope they prove useful to some.