**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

*Submitted for publication*

**More on Bases of Uncountable Free Abelian Groups**

*To appear*

### Theses

**On the Definability and Complexity of Sets and Structures**

*PhD thesis*

**Topics in Set Theory and Logic**

*Master’s thesis*

### Talks

**The Borel-Definable Group Cohomology of ℝ**

^{n}Is (Hopefully) Simple*IMS Graduate Summer School in Logic, National University of Singapore*

**On CA-Recursion and Marstrand’s Theorem**

*Victoria University of Wellington Logic Seminar*

**Co-analytic Counterexamples to Marstrand’s Projection Theorem**

*Penn State Logic Seminar*// online

*National University of Singapore Logic Seminar*// online

*Computability Theory and Applications Seminar*// online

**On (Borel) Group Extensions**

*University of Sydney Graduate Talks in Topology and Geometry (GT)*// online

^{2}**On Homological Algebra, Group Extensions, and Descriptive Set Theory**

*Victoria University of Wellington SMS Graduate Seminar*

**When the Search for Proofs Turns Futile**

*Victoria University of Wellington SMS Graduate Seminar*

**Higher Derived Limits and Cohomology of Ordinals**

*Victoria University of Wellington Logic Seminar*

**Computability, Complexity, and Some Algebra**

*NZMASP 2019, Wainui*

**More on Bases of Uncountable Free Abelian Groups**

*Victoria University of Wellington Logic Seminar*

### Miscellaneous

**Short Teaching Notes**

^{3}is a union of disjoint circles, assuming AC

**Doctoral Proposal**

*Victoria University of Wellington*