MOPper World 2.0

About MOP#

This section of the website is dedicated to public-facing material from various years of MOP. It’s similar in spirit to the MOPper world that ran between 1997 and 2004. This page isn’t a puzzle.

The 2025 MOP is hosted by IMSA. Between 2015 and 2024, MOP was at Carnegie Mellon under Po-Shen Loh, besides 2020 and 2021 when the camp was run on Discord due to COVID-19. Prior to 2015, the camp was in University of Nebraska-Lincoln.

See FAQ CR-7 for approximate invitation criteria.

I am currently the assistant academic director of MOP. (There is no academic director or assistant director.) Staff includes instructors, RA’s, and teaching assistants (aka graders).

For many years, the official name for MOP was “MOSP”, but the letter S was universally ignored by staff and students, and its omission became an ongoing gag. The S was finally officially deleted in 2017.

T-shirt designs#

Traditionally, MOP T-shirts are printed in black on grey. Except for 2020 and 2021, there is usually only a front design, and the back contains everyone’s signature.

Problems#

The ELMO is written by returning MOPpers for new MOPpers, featuring “teams” and coordination. See ELMO page.
The Mock IMO is run by staff using ISL; it also features a mock coordination. It’s one of several practice tests run by the staff at MOP each year. You can download the problems here:

The staff also provide MOP homework to work on before camp starts, mostly for fun and so people have something to talk about at airports. Here are recent homework problems:

Schedules#

Here are calendars for recent years of MOP:

For more concrete times, here was the 2022 weekday timetable as an example (which should be read alongside the 2022 calendar):

07:00-09:00 Breakfast
09:00-10:30 Morning class 1
10:40-12:10 Morning class 2
12:10-13:20 Lunch
Exactly one of:
- 13:20-14:50 Afternoon class,
- 13:20-17:50 Mock olympiad / Team Selection Test, OR
- 13:20-14:00 Assembly meeting (for announcements, etc.)
17:00-20:00 Dinner hours
19:15-20:00 Test review (presenting solutions to test problems) OR seminar on higher math (both optional)
22:30-23:00 Evening check-in

There is a lot of free time built into the schedule, and this is intentional. Some examples of recent activities include singing troupe (see below), the double-elimination fish tournament, the plank countdown, trips to Waffallonia, dance tutorials, live-action Mafia and StarCraft (both no longer banned), and too many water balloons.

Singing troupe#

The MOP Singing Troupe is a tradition dating back to around 2010, started by Evan o’Dorney; it starts and ends the closing ceremony. Here are recent songs we performed:

K-MOP#

I would say this was not my idea, but that would be a lie.

MOP Puzzle Hunt#

mosp.evanchen.cc hosts:

A miniature one-round hunt written by Evan Chen, Isabella Quan, Sanjana Das, and Serena An for MOP 2021.
A 2022 puzzle hunt led by Luke Robitaille.

Quotes#

Alex: “That isn’t a hypercube, that’s two Pringles and two lines.”
Alexander: “I hate transition metals”.
Andrew: “I ate transition metals.”
Aprameya: “I want to thank my mom for giving me this hair and my dad for being bald.”
Andrew, to Two Sigma speaker: “Is the company mail service called sigma mail?”
Benny: “I looked left, I looked right, then I realized I didn’t remember the cubic discriminant”.
Carl, to Luke about his LaTeX usage: “There are no excuses to a crime of this magnitude for a man of your stature.”
Daniel: “We should have told them we’re shuffling Red 1 and Red 2, and then just swap Red 1 and Red 2”.
David, while eating cereal for dinner: “Cereal is objectively a lunch food but the waffle machine is broken.”
Evan: “okay by popular request we’re shuffling Red 1 and Red 2 🎲
i’m sorry for the last minute notice since i’m sure you’re all asleep by now 🌙 but good morning 🌞
If you’re a student in red, to determine your new group:
• Convert each letter in your first and last name via A1Z26 and take the sum
• You’re in Red 1️⃣ if this sum is a quadratic residue modulo 239, and Red 2️⃣ otherwise.
If you need help computing the Legendre symbol, either use Python builtin pow, or quadratic reciprocity if you want to do it by hand. (We don’t recommend ChatGPT. We tried it and it had 50% success.)”
Gloria: “Everything is a fork if you stab hard enough.”
Gloria: “I bought 24 copies of Anki, so I can have different decks open and stuff.” (It cost \$480.)
Henry: “Is Evan Chen bad for your lungs?”
Henry: “Sorry, but I can’t read your name tag because I’m black-white colorblind.”
Henry, to Hannah: “Your hair is a defense mechanism!”
Jordan: “Are we sides of the quadrilateral formed by the other 4 intersections of a conic with 2 circles that intersect at 2 points on the conic? Because we never meet.”
Jordan: “Why does GeoGebra name my point B'''_3??”
Julia: “I saw a woman with orange hair and thought she was a live size red panda.”
Krishna: “No, it’s actually kind of hard. But yeah, it’s trivial.”
Linus Tang:
- Exhibit A: 0.4 style score
- Exhibit B: 3 staples
- Exhibit C: 1 more staple
- Exhibit D: the other staple (front)
- Exhibit E: request for style points (denied)
- Exhibit F: Table of contents
Mingyue: “Your hyperbola got you seven points. I don’t get it, I thought you could only pass it through five.”
Mingyue’s rap during talent show
Owen: “Life is not a mountain of pain but a valley of fun.”
Raz: “The Schiffler point is the leader of the Libertarian party.”
Richard: “I really don’t like eigenvalues.”
Ritwin: “When do you think the last time I did integral was?”
Henry: “Wasn’t integration completed in 1964?”
Jonathan: “Before 1964 did they use Riemann sums?”
Henry: “Yeah they split into parts.”
Wendy: “All food is edible, you just die because your body’s a skill issue.”
Wendy: “I’m not getting to let the word xooks outlive me.”
Wendy: “I trust your oddness more than I trust my oddness”
Zack: “Here’s some fact about circle points.”
Alexander: “You can Cayley-Bacharach with them.”
Zack: “That is not a fun fact about circle points.”

Aaryan: “Showering is a 35 MOHS task.”
Alec: “What are some characteristics of a buffalo?”
Andrew: “It touches grass.”
Allen: “If I slept for the entire day I would have swept the test in 2 hours.” Elliott: “If you sleep for 24 hours, you’re dead.”
Allen: “I visualized the 770070 on the scoreboard, but if you visualize something for too long it becomes a reality. So I stopped visualizing and solved the problem.”
Aprameya: “We’re not nice people, we’re geometry mains.”
Derek: “When I see a geo problem with circumcircle gamma, I lose the gamma.”
Derek: “Why are we complex bashing combo problems?”
Enrico: “Sometimes I think I’m too stupid to be this smart, and sometimes I think I’m too smart to be this stupid.”
Evan: “What year?”
Milan: “Twenty-something.”
Evan: “Gee, thanks!”
Henry: “Hey Razzi, I saw your handwriting. Are you going to med school?”
Razzi: “No, I don’t think so.”
Aaron: “What a waste of talent.”
Henry: “This orzing was sponsored by Raid Shadow Legends.”
Krishna P.: “Moving points moves your points from 7 to 0.”
Luke: “It should be obvious that a job is work, but it never really hit me.”
Po-Shen Loh: “It’s a lot easier to get good grades when you have two classes.”
Po-Shen Loh: “How many MOPpers does it take to do trigonometry?”
Neal, on Krishna’s messy geometry diagrams: “But he uses nuclear weapons, so it doesn’t really matter.”
Tristan (44 minutes before class ends): “For sake of time I will go over the solution.”
Vivian: “Evan Chen is the new 🐭.”
Yotam: “Bashing turns geo into points.”
“If we are clowns, then dotted is a walking circus.”
“To solve problem 2, it is not enough to not be a potato. You have to be a napa cabbage.”

Franklyn Wang: “Evan has contributed to a decrease in Resnik’s reputation.”
Brandon Wang: “Evan is not solely responsible, right? Others are also responsible.”
Franklyn Wang: “Yeah, like Resnik.”
Luke Robitaille: “I did not make ARML tiebreakers as a 12-year-old this year.”
Staff: “Let O be a point inside cyclic quadrilateral ABCD. Diagonals AC and BD intersect at P. Let X be the isogonal conjugate of B with respect to ODP. Show that one of the two points X and B lies on BX.”
Also staff: “Alice says, ‘you are a doofus’. Bob says, ‘no you’. Compute the total number of words exchanged.”
Milan Haiman: “This is a 2-page solution right?”
Po-Shen Loh: “No, it’s 15.”
Sign on the way to breakfast: “Statue removed for restoration.”
Espen Slettnes: “What statue? I don’t see it.”
Andrew Lin: “There’s nothing wrong with light mode.”
Luke Robitaille: “Some people should sing louder. This is Singing Troupe, not Singing Luke.”
Found on a fortune cookie: “Hard work pays off in the future. Laziness pays off now.”
Kevin Wu: “Their corn tastes more like their garlic bread than their garlic bread does.”
Franklyn Wang: “As Winston Churchill said during World War Two, ‘If you’re going through hell, keep going.’ That’s what you do for this problem.”
Evan Chen, while teaching class: “I can’t wait for class to end.”
Rachel Zhang: “Evan’s like, tiny, right?”
Henry Jiang: “I lose everything. One time I lost something, and then someone picked it up, and then he lost it, so I found it again.”
Jeff Lin: “Teaching your four-year-old to drink is like teaching your eight grader bary.”
Po-Shen Loh: “And I think this is a lesson we can all learn from, especially for the IMO team: when you do something, do it with full commitment.”
Luke Robitaille: “So basically, you’re saying that a full commitment is what you’re thinking of?”
Franklyn Wang: “Do piranha plants exist? Or are they just a Mario thing?”
Holden Mui: “How’s the corn?”
Po-Shen Loh: “It’s very dehydrated. It’s like they forgot to add water.” Sophie Liu: “I described it as pieces of matter that just so happen to be yellow.”
Derek Liu: “If four of you took 7 days to solve ELMO 6, by pigeonhole one of you took only one day to solve it.”
Cordelia Hu: “Any solution is a one-liner if the line is sufficiently long.”
Evan Chen: “Aren’t lines supposed to be infinite in length or something?”
“One day [Resnik] had corn, then the next day they had corn with green beans, and you could clearly tell it was yesterday’s corn. Then the next day they had fried rice with corn and green beans.”
Feodor Yevtushenko: “This rice tastes like rice except one in every like 20 grains is uncooked.”
(Derek Liu: “Did you mean one in every 20 grains is cooked?”)
Many people: “Mr. Turtle, Mr. Turtle, come out of your shell @Holden”
Brandon Wang: “A bunch of geo people are good at bashing; then they are the committee and write problems that can’t be bashed; then the students can’t bash; and the circle continues.”
Henry Jiang: “If you play a wrong note really loudly, that’s just called jazz.”
Jeff Chen: “It’s not wrong, it’s just misguided.”
Jeff Chen: “Walking is nontrivially hard. It’s $O(n)$ effort, whereas sitting here is $O(1)$ effort”
Jeff Chen: “I’m too high; I’m going to go run around.”
Victoria Hu: “Oh yeah didn’t u donate Raina to me at the airport?”
Debbie Lee: “I don’t think Jane Street would appreciate all their thousands of dollars going to fruit snacks.”
Derek Liu: “Dude, I haven’t made a single haiku in all of MOP. What the heck.”

Nebraska trip#

In 2018, I flew back to the University of Nebraska-Lincoln the weekend before MOP to visit the venue again, since that was where MOP was held when I was a student. You can see photos of the Nebraska venue if you want to see why I keep saying things were better in the good old days.

The dorm we stayed in was called Neihardt Hall, and it had four sub-halls inside it named Heppner, Love, Piper, and Raymond. We had a lot of different lounge spaces, which also had names:

The Blue Room was the primary lounge on the ground floor, which was where orientation was held and a lot of activities.
There were side lounges on the ground floor called the Grey Parlor, the Gold Parlor, and the Sun Room, among others. We held singing troupe here since there was a piano.
There was an old-fashioned elevator with a curtain-like door that you pulled by hand. That elevator was labeled “OTIS”, and my training program is secretly named after this elevator.
The ground floor had a bunch of small classroom areas where test review used to be held. In addition to the red paintings, they had these little coasters, and people would throw them around a lot.
There was a meeting room with a green chalkboard where we held all the ELMO meetings.
The basement had a stage with some tables and chairs nearby where we held the ELMO and the talent show, as well as another giant lounge area nearby complete with several sofas, another TV, and a pool table.
Neihardt Hall itself enclosed a little garden area, that you could go outside and walk around in.

Also, the Selleck dining is amazing. Just saying.

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Updated Wed 2 Jul 2025, 00:10:49 UTC by 997e6f320ef4

Evan Chen《陳誼廷》

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