Russian Combo
A fun unit involving combinatorics problems from Russia.
Unit Overview
Russian Combo, as the name suggests, is filled with combinatorics problems from Russia. These are characterized by unusually short, low-tech solutions that only require ingenuity, so don't worry if you don't know big name theorems and techniques like Hall or Combo Null. There is usually one main idea behind each problem, and once you figure it out the whole thing "cracks open" and falls apart.
These problems are also very diverse, fitting many other combo units including Global, Local, Equality, Graph Theory, and more. There is a decent amount of combinatorial geometry as well.
Notable Problems
Some notable problems in this unit include:
- Russia 2014/10.7 - Representative of the general idea of this unit, with a nice twist
- USEMO 2019/5 - Famous patriotic/dazzling polygon problem. Representative of the "hard but simple idea" trope
- USEMO 2020/2 - Famous Calvin and Hobbes game theory problem. Somewhat trickier to get a grip on, but falls apart once you realize the main idea
- Russia 1998/10.8 - Beautiful problem, hard to categorize without spoiling the solution.
- Wallace Bolyai Gerwein - Brain hurting
This unit has a minimum amount of required clubs as 36, if you have time 45, and a maximum of 120.