Monday 5th October 2020

Ethan Ng: IMO 2020 Report

General IMO 2020 was my first and last IMO, since I won’t be eligible in the coming years. Going into IMO for the first time I didn’t have much experience with how the procedures worked, so I just did what I could and tried my best. In general I think the IMO process this year was somewhat suboptimal but still pretty good, and I’m mostly happy with how it turned out.

Training After camp I started the NZ Squad training program. The NZ Squad training this year was somewhat different to previous years, in that instead of having one problem set with 4 problems every week we would instead get an alternating schedule with a lesson one week and an assignment due the next week. It was somewhat suboptimal because sometimes the scheduled tutors didn’t have lectures so we didn’t get a theory session, but we still always got the problem sessions so it was fine I suppose.

I started grinding IMO Shortlist questions around May-June, which was around when the CMC was. I think one of my main regrets in this sense is starting so late - I knew people who started last year or even a few years ago, and that’s really allowed them to build up enough intuition to tackle much harder problems. I’m not sure (since I can’t repeat my IMO training) but I feel like if I’d started grinding ISL earlier I might have done better, since I improved decently much in the 3 months I did do ISL problems.

Competition Days I don’t think there’s really much to be said about the competition days. I’d done mocks in the past, so sitting the contest wasn’t really much different from the mocks I’d done. You would sit in the room for 4 and a half hours and solve (or sometimes just attempt to solve) maths problems, with the occasional toilet break or snack. The act of sitting papers felt really routine to me and I think it was probably the least exciting part of the IMO.1

Post-contest sadness and anxiety Of course, after the contest everyone’s keen to discuss how the problems were solved and how they thought they did. Personally I thought I did decently solving Q1 and Q4, but I felt that Q2 and Q5 were definitely within my reach as well, and for that I was somewhat disappointed in myself. I believe a lot of other people shared the same feeling of having done the weighted AM-GM in Problem 2 but failing to solve it from there even though expanding and bashing did indeed work. For Problem 5 I think I did one step of the induction but failed to generalise it.

I think it’s one of the worst feelings to know that you could have solved a maths problem but you didn’t. If you solve a problem, you’re happy, and if you didn’t solve because it was too hard, you’d just tell yourself "I would never have solved that anyway". But in problems you think you can normally solve, you might just miss a step, or not view the problem in particular way - or some other small complication might stop you from solving the problem - and I think that’s one of the worst feelings when doing olympiad maths.

I think what you have to do in this kind of situation is just accept it, think about how you could see it in the future, and move on. I think trying to move on has a somewhat calming effect, and doing other things helps to relieve some disappointment you might feel. I have a theory that this is why maths olympiad people enjoy playing games after exams - it’s to drown out the sadness of a possibly disappointing result.

Social aspects This year2 the social aspect of IMO was somewhat suboptimal since we were all in different places - you don’t get to meet people from other countries in person any more, and we didn’t even get to meet the people from Auckland, since they had to stay together. However I don’t think it was too bad, since with the new "modern technology" we can communicate and play games with each other over the internet. I remember all of us (including team leadership) playing Among Us together on the first night - it was really fun.

Excursions As is usual, this year the host country (Russia) organised excursions for us. However due to the suboptimal timing of the excursions (some were at 3-5am for us), the NZMOC decided to organise their own excursion for the Christchurch people. Personally I found this really fun and was definitely a highlight of the IMO. On the day after the IMO, we went out to mini golf. We also went on one of those 4-person bikes which was amazing, I’d never experienced that before and going around at > 20 kmh−1 was such a thrill.

Of course some Russian excursions/events were at a reasonable time for NZers too. I enjoyed listening to the interviews and hearing what these great mathematicians had to say about IMO and mathematics in general - it was pretty interesting and inspirational. However I feel like some of the other events were sub-optimal, they just didn’t really feel that fun or interesting. I think the chess tournament would have been fun except we missed our first match by not waking up in time, which was very suboptimal.

Post-results I thought that results would come out after the final jury meeting at 1am on 28 Sep, so I decided to stay up late to wait for results instead of sleeping. I projected myself on the borderline of bronze and HM, so I was pretty anxious about whether I would make the bronze cutoff or not. I remember people predicting that the bronze cutoff was going to be 16-18, and although I definitely got 7 for Q1 and Q4 at that point some of my partials were pretty dodgy (like not explicitly stating weights for Q2). I didn’t know whether I would make bronze or be just under. I thought that in the best case scenario I could scrape 721710 if all the partials were given, so that’s what I hoped for.

When the results came out I was pretty surprised. Of course, with everyone trying to access it at once, the IMO website became pretty slow, but I eventually managed to see the cutoffs and my score. The bronze cutoff was only 15 and I’d gotten the 18 points I’d hoped for, which meant I got a solid bronze. Although I didn’t get Q2 or Q5 (getting both would net a silver in this scheme) I was pretty satisfied with the bronze I got.

Closing thoughts I enjoyed IMO 2020 this year. I’d definitely recommend it to anyone who has a chance to go. If you’re into maths, I think that IMO is a wonderful experience with amazing problems. In addition, the social side is pretty cool too. Although I didn’t get to meet contestants from other countries in person, I met them online which I feel was a suitable replacement.

1 Here’s a clarification: I’m not saying that the paper was not exciting, I’m saying that the the act of sitting an exam isn’t very exciting. Of course the problems were fun! (well most of them, anyway)
2 Note that I don’t have a reference to compare this to, since I haven’t been to any previous in-person IMOs - so take comparisons with a grain of salt