Sida Li

BIG Scholar 2024 | IMO Medalist

Major and Institution
Mathematics at Trinity College, University of Cambridge
Achievements
IMO Bronze 2022, IMO Bronze 2023
High School
Reading School
Country
United Kingdom
One Aspiration
Research at the intersection of geometry, combinatorics and number theory
Hobbies
Badminton, Mao
Sida Li

BIG Scholar 2024 | IMO Medalist

The beauty of geometry and drawing pulled Sida into a love of math. Mentors and support from state schools and the UK Maths Trust helped him develop his talent. Now at Cambridge, he has a packed research agenda across multiple fields and is charting a course toward academia. But he still finds several hours a week to compete at a high level in his favorite sport.
We caught up during the school year (interview edited for length and clarity):
GTF: Hi, Sida. How are you enjoying Trinity?

SL: My first year was good. The second year is busier, but I'm enjoying it so far.

GTF: Take us back to when you first started doing math. What sparked your interest?

SL: In the UK, we have a really nice outreach system for the maths Olympiad and maths challenges. I thought those were really nice problem solving activities. From Year 10 or 11, I was interested in Euclidean geometry – drawing circles and triangles and intersections. Geometry is quite beautiful. Very elementary proofs, but also many coincidences you want to explore. Every year, there were challenges which led to Olympiads. The UK system gives a lot of support to students in the younger years.

GTF: Tell me more about that support and what was most helpful to you in your math journey.

SL: A turning point for me was in Year 11, I believe, when I was invited to a UK Maths Trust program where they pair you with a mentor who has done competitions before. I was really fortunate that my mentor was also quite young in university, and had time to help me progress very rapidly. They were also very good at geometry, spurring on my passion for that subject.

GTF: What are your favorite memories from competitions?

SL: One that made a big difference for me was the Balkan Math Olympiad. I didn't think I was good enough. But I got quite lucky, I'd say, on one of the selection tests, and made it to that competition, which the UK often uses to help new and upcoming students gain experience. That was really fun, because it was six of us who didn't have much experience. It was my first time going to another country for a competition, and it was a lot of fun.

My favorite memories are relaxing after the exams are over, getting to know the other countries and meeting people. We'd mix together, people from loads of different countries, and play a lot of Mao, a traditional camp card game.

GTF: Did your performance at the Balkan Olympiad help you make the IMO team the same year?

SL: The UK is quite secretive about how they select the teams, but yeah, I did quite well on the Balkans. And there was a lot of geometry on the team selection test for the IMO itself. I was very happy with that, of course.

GTF: From that interest early in Euclidean geometry up to now, have your mathematical interests changed?

SL: Euclidean geometry is a very Olympiad kind of thing. It gets you into proofs and solving problems creatively. At university, you start learning more content-heavy topics, building the foundations to branch out in maths. So I still dabble in geometry. But since coming to uni, I've enjoyed the pure courses – analysis and topology. There’s a lot of abstract algebra, like groups and rings.

I want to pursue research in maths. I still haven't decided exactly which topics, but I'm interested in doing something at the intersection of geometry, combinatorics and number theory.

GTF: Given your interest in research, what do you want to do over the summer and beyond? Are you considering a Ph.D.?

SL: I’ve been very fortunate to get a good taste of maths research already. I worked in Trinity’s Summer Research in Maths program, on a project in algebraic combinatorics – analyzing graphs via their adjacency matrices. That was really fun! In hindsight, a very perfect project for me to start with.

This summer, I'm doing two research projects, which might be quite busy! First is the New York City discrete mathematics Research Experience for Undergraduates program. It’s what I was just talking about–research at the intersection of combinatorics and geometry. We’ll be mixing combinatorial ideas and even some algebraic ideas into analyzing points, lines and their incidences and other ideas in geometry. As a non-US student, I'm very grateful to Global Talent Fund for funding my stipend for that program. Then I’ll be back in Cambridge for a more pure project in combinatorics.

Farther out, I’ll complete my current three-year degree, then probably go on to a fourth year here. But I might also apply to grad school in the US, or go on to a Ph.D. in the UK.

GTF: Looking outside of math, what are your hobbies and interests?

SL: I spend like four or five hours a week playing badminton. I'm a very big fan! Funnily enough, for as big of a college as Trinity is, our badminton team isn't particularly good. So during first year, I was incredibly lucky to get invited to the first team. It’s great–I get to play at a high level on Mondays with the first team, and then other times in the week. I've got a bunch of friends who play. A lot of mathematicians in Trinity play badminton as well as adjacent friend groups. It’s a way to stop thinking about maths and let my brain run free.

GTF: That’s cool. Any final thoughts on Trinity?

SL: I feel really privileged to study Trinity. There's such a great community of mathematicians, in my year, and below and above. Even though everyone’s working hard toward the same goal, there's no sense of competition. Everyone’s helping each other out.

And our Math Society is rich in history, and really well organized. So we get to see incredibly famous faces basically every week, who give talks. That’s also really inspiring.