Chung Lok Andrew Ng

Hi! My full name is Chung Lok Andrew Ng, but I usually just go by Andrew unless I’m trying to avoid getting confused with an AI scientist. I am a final year PhD student at the University of Bonn. My research interests are best described as an open neighbourhood of geometric group theory. You can contact me at clan [at] math.uni-bonn.de.

Preprints/Publications

1. Outer automorphism groups and the Atiyah Conjecture (with Sam P. Fisher, 2026) arxiv
2. Improved algebraic fibrations of high-dimensional hyperbolic groups (with Giovanni Italiano and Matteo Migliorini, 2026) arxiv
3. Cobordism, spin structures, and profinite completions (with Sam Hughes, 2026) arxiv
4. Quasi-convex surface subgroups in some one-relator groups with torsion (BLMS, 2026) arxiv journal
5. Virtual First Betti Number of GGS Groups (Journal of Algebra, 2026) arxiv journal

Other Writing
I believe that exposition is a central part of a mathematician’s work, so I have written up some notes on various topics which I found interesting and hope that they might be of use to people who come across these. I apologise in advance for any errors.

• I did a summer research project on random groups under the supervision of Calum Ashcroft. The report can be found here. Note that better results have been obtained.
• Lagrange’s 4-squares theorem
• Bass-Serre theory
• Combinatorial Morse Theory
• CAT(0) cube complexes
• Notes on complex hyperbolic lattices for a reading group, loosely following unpublished notes of McReynolds.

Organisation
I am co-organising the Geometrische Gruppentheorie Oberseminar at Bonn with Lawk Mineh in WS 2026. The seminar website is here.

I am one of the local organisers for the conference Interactions between algebraic geometry and geometric group theory. The conference website is here.

I have organised the following reading groups at Bonn:

1. Open Problems Seminar 2024.
2. Bounded cohomology SS (Sommersemester) 24.
3. Buildings WS (Wintersemester) 24/25.
4. JSJ decompositions SS 25. The notes for this are available on this blog.
5. General Knowledge Club SS 26.

Teaching
I was a TA for the course Einführung in die Geometrie und Topologie in SS 24.

Outreach
I have helped mark mathematics Olympiads for secondary school students at a national and international level. I was on the Problem Selection Committee for IMO 2024. Over the past years I have taught at the annual maths camp organised by UKMT at Trinity College, Cambridge. The teaching material I used for this is available upon request. I have also been a guest writer for this blog on Olympiad mathematics.

Other

• The most fun maths and art crossover I have ever seen has to be the widget on Jonathan Fruchter’s homepage.
• While a student at Cambridge I helped make knotted dumplings. Photos can be found here, although Gheehyun’s later experiments have been much more elaborate.