Evan Chen's Olympiad Handouts
Evan Chen is a multiple-time IMO gold medalist and one the authors of many freely available olympiad study material. His website hosts handouts covering every major olympiad topic, written from the perspective of a top competitor and coach.
He also runs OTIS (Olympiad Training for Individual Study), a selective training program, and is the author of the widely used geometry textbook Euclidean Geometry in Mathematical Olympiads (EGMO).
What's Available
General
A few broadly useful handouts for anyone starting out:
- Unofficial syllabus for math olympiads — an overview of what topics usually appear in olympiad competitions
- Notes on proof-writing style — used at MOP (Math Olympiad Program), covers how to write clear and rigorous solutions
- Intro to Proofs for the Morbidly Curious — a guide on how mathematical proofs work in theory and practice
Algebra
- Introduction to Functional Equations
- Olympiad Inequalities (with an original Chinese version)
- Monsters — pathological functional equations
- Lagrange Multipliers Done Correctly
- Summation — sums, products, and generating functions
Geometry
- Barycentric Coordinates in Olympiad Geometry — one of his most-cited handouts; introduces barycentric coordinates from scratch
- Bashing Geometry with Complex Numbers — the classic complex number method for geometry problems
- How to Use Directed Angles — a short but essential note on a technique that trips up many competitors
- A Guessing Game: Mixtilinear Incircles — properties of mixtilinear incircles presented interactively
- Constructing Diagrams — advice on drawing useful diagrams for geometry problems
Combinatorics
- Expected Uses of Probability — expected value and the probabilistic method, inspired by IMO 2014 Problem 6
Competition Journals
Evan Chen also published detailed accounts of his competition experiences, including thought-by-thought solution analyses:
- IMO 2014 Journal
- Taiwan TST 2014 Reflection
- USAMO 2014 Contest Analysis
EGMO Book
Euclidean Geometry in Mathematical Olympiads is a full textbook on olympiad geometry. It is one of the most comprehensive resources on the subject and is freely available as a PDF on his site.
Tips
- Start with the beginner's page if you are new to olympiads — Evan Chen wrote a curated guide specifically for beginners.
- The handouts are LaTeX-typeset and very polished; they read more like mini-textbooks than rough notes.
- Even if a topic isn't on your immediate priority list, his proof-writing and syllabus handouts are worth reading early.