Previous Events!

The Probabilistic Method by Abhay Bestrapalli

In this session, we learn to apply probability in olympiad questions. We learn how to use probability, expectation, pigeonhole, and more. We apply these methods in many olympiad questions. There are no hard prerequisites.

January 30, 2022 | 08:30 (EST) 19:00 (IST)

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Number Theoretic Sequences by Pranjal Srivastava

Incorporating 'rigid' ideas, in this session, we will analyze various number theory sequences that have appeared in problems, and see what properties those sequences have. No hard prerequisites.

January 29, 2022 | 08:30 (EST) 19:00 (IST)

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Elementary Geometry by Rohan Goyal

We do some basic constructions and used basic properties to prove the existence of some major triangle centers like circumcentre, orthocentre, etc, and solve a few problems from olympiads and prove some nice results as well. No hard prerequisites.

January 23, 2022 | 08:30 (EST) 19:00 (IST)

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Fairy Sequences by Atul Shatavart Nadig

Yes, now fairies can be found in olympiad math! We'll discuss some cool properties of farey (fairy) sequences (which are essentially reduced fractions between 0 and 1) and ford circles, followed by a bunch of olympiad problems using them. Prerequisites include knowing what a number is.

January 16, 2022 | 08:30 (EST) 19:00 (IST)

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Vector Spaces and Linear Transformations by Arindam Bhattacharyya

We introduce the notion of a dimension of a vector space, linear transformations, quotient spaces, first isomorphism theorem, eigenvalues, and the characteristic polynomial. If we have time left, we talk about what a general linear map looks like and in particular the Jordan canonical form.

January 15, 2022 | 08:30 (EST) 19:00 (IST)

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An Introduction to Barycentric Coordinates by Krishna Agaram

We take a look at what these are actually doing and build a strong theory. Finally, we see its power by deriving some well-known results in seconds via this technique and solving questions. No hard prerequisites.

December 26, 2021 | 08:30 (EST) 19:00 (IST)

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The Chinese Remainder Theorem by Aditya Khurmi

This talk focuses on giving an intuition of why the result holds true and seeing its real power through examples. The key idea here is in construction-type problems where you "freely do what you want and let CRT do the rest". More handouts in the YT description.

December 25, 2021 | 08:30 (EST) 19:00 (IST)

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Probability and Expectation by Tejas Mittal

We start with Probability spaces and build up till linearity of expectation (for discrete random variables). We find and solve apply this theory in Olympiad problems. No hard prerequisites.

December 19, 2021 | 08:30 (EST) 19:00 (IST)

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Pell's Equations by Ojas Mittal

We analyze and solve the famous Pell's equation x^2-d*y^2=1 for integers x,y. We also see some applications in Olympiad problems. There are no hard prerequisites.

December 18, 2021 | 08:30 (EST) 19:00 (IST)

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Graph Theory Paths, Cycles, and Trees by Shourya Pandey

This was a session on graph theory and was conducted by Shourya Pandey. We discuss (Olympiad) problems related to paths, cycles, with a special emphasis on trees and possibly other sparse graphs. No hard prerequisites.

December 05, 2021 | 08:30 (EST) 19:00 (IST)

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Intro to Combinatorial Geometry by Rohan Goyal

Combinatorial Geometry is the application of geometric concepts to combinatorics. We go over various ideas and concepts in the subject with the help of many questions from the olympiads. There are no hard prerequisites. Prerequisites: Basic Maturity

December 04, 2021 | 08:30 (EST) 19:00 (IST)

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Density in NT by Pranjal Srivastava

This was a session on the use of "density" in number theory and was conducted by Pranjal Srivastava. We do various size-related things. Our motto is "If it's not false that often, must be true somewhere". Prerequisites: Basic Maturity

November 21, 2021 | 08:30 (EST) 19:00 (IST)

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Intro to Inequalities by Luke Robitaille

This was an introductory session on inequalities and was conducted by Luke Robitaille. We cover some basic facts about inequalities and solve some inequality problems from contests. No major pre-requisite except basic maturity is assumed.

November 20, 2021 | 09:30 (EST) 20:00 (IST)

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The Magic of Conics by Krishna Agaram

An intro to the fascinating Conic Sections, from the point of Projective Geometry. We first cover some basic projective geometry, and then prove some nice results about conics, including the famous Pascal's Theorem. We also conjure formulae for equations of the tangent, chord of contact, etc

November 14, 2021 | 07:30 (EST) 18:00 (IST)

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Spectral Graph Theory by Rishabh Dhiman

This is a session on Spectral Graph Theory and was conducted by Rishab Dhiman. We introduce Laplacian and Adjacency matrices of graphs and use their eigenvalues/eigenvectors to get information about the graph's structural properties. Few bounds will be proved relating eigenvalues with graph ...

October 30, 2021 | 08:30 (EST) 19:00 (IST)

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Recursion and Generating Functions by Krishna Agaram

We apply generating functions to solve linear recurrence relations. Using Exponential Generating Functions, we solve more problems and discuss the roots of unity filter. We look at the superpower of Multivariate Generating Functions. No hard prerequisites.

October 24, 2021 | 08:30 (EST) 19:00 (IST)

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Directed angles by Anish Kulkarni

In this introductory geometry session, we introduce the important but tricky concept of directed angles. We see its definition and uses and then solve olympiad problems involving their use. There are no hard prerequisites.

October 23, 2021 | 08:30 (EST) 19:00 (IST)

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An Introduction to Number Theory by Apar Ahuja

We go through the basics of modulo arithmetic, residue systems, and linear congruences. We also explore the Chinese remainder theorem and introduce you to quadratic congruences. No hard prerequisites. Apar is a third year computer science undergraduate at IIT Delhi.

October 09, 2021 | 08:30 (EST) 19:00 (IST)

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The Second Easiest Million Dollar Question by Shourya Pandey

If you have ever tried newspaper puzzles, you know that solving a sudoku puzzle is harder than checking if the solution given at the back of the newspaper is correct or not. Why is it so? Enter the complexity zoo, is P = NP?

November 13, 2021 | 08:30 (EST) 19:00 (IST)

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Groups Through A Symmetrical Lens by Rajdeep Ghosh

This session is an introduction to groups through symmetries and was conducted by Rajdeep Ghosh. We discuss the subsequent motivation for the classical description of a group. We also go through group actions and a very natural presentation of Cayley's theorem. No hard prerequisites.

November 07, 2021 | 08:30 (EST) 19:00 (IST)

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Elementary Olympiad Geometry by Kazi Aryan Amin

This is an introductory olympiad class on geometry and was conducted by Kazi Aryan Amin. We will provide a comprehensive introduction to olympiad geometry along with various lemmas, ideas, and concepts. And lots of contest questions. No hard prerequisites.

November 06, 2021 | 08:30 (EST) 19:00 (IST)

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Max Flow Min Cut Part 2 by Aatman Supkar

This was the second session on Max Flow Min Cut and was conducted by Aatman Supkar. We revise the content from the last class, and we proceed to discuss the theorem in a more general context, with a couple of applications.

October 31, 2021 | 08:30 (EST) 19:00 (IST)

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Gaussian integers come home for Christmas by Writika Sarkar

Which natural numbers can be written as a sum of two integer squares? We are going to be better than Fermat and see how this question naturally takes us to the realm of Gaussian integers, which we discuss in some detail, and witness an effortless proof of Fermat’s theorem weaving itself.

October 17, 2021 | 08:30 (EST) 19:00 (IST)

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Change is Not the Only Constant (Invariants) by Rajdeep Ghosh

The talk is an introduction to the ideas of invariants and mono variants which are fundamental heuristic tools in mathematics and feature commonly in Olympiads. No hard prerequisites. Apar is a third year computer science undergraduate at IIT Delhi.

October 16, 2021 | 08:30 (EST) 19:00 (IST)

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Order modulo a prime by Pranjal Srivastava

This talk introduces the notion of the order of a number modulo a prime. We prove a few related results including the existence of a primitive root and then a few problems involving orders. The prerequisites are basic number theory. Apar is a third year computer science undergraduate at IIT Delhi.

October 10, 2021 | 08:30 (EST) 19:00 (IST)

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Divide and Conquer by Niyanth Rao

The talk focused on the divide and conquer technique, specifically with an eye towards fast exponentiation. Time permitting, we look at a few other uses of the idea as well. No hard prerequisites. Niyanth Rao is a college freshman at Carnegie Mellon University studying Math and CS.

October 03, 2021 | 07:00 (EST) 17:30 (IST)

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Combinatorial Number Theory by Milica Vugdelić

We cover various well-known results and theorems like Cauchy-Davenport and Van der Waerden with their applications. We also solve a ton of relevant and interesting problems. No hard prerequisites except general problem-solving experience.

October 02, 2021 | 08:30 (EST) 19:00 (IST)

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When a Plane met a Cone by Aditi Muthkhod

We start by building intuition about a nontrivial well-known result in conics and watch as things fall naturally in place. We then return to the result in question with Dandelin's magic and watch how things unfold to give a beautiful proof. The prerequisites are knowing what a cone is.

September 26, 2021 | 09:30 (EST) 19:00 (IST)

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Length at length by Aniruddhan Ganesaraman

This is an expository talk on Measure Theory- the art of assigning sizes to sets in a no-nonsense fashion, generalizing well-known concepts like length and area. We also explore how interpretations of length have evolved from time immemorial to what it is now.

September 25, 2021 | 09:30 (EST) 19:00 (IST)

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Combinatorics PSS by Vedant Saini

This will be a problem-solving session with combinatorics questions. We will try to find and motivate the solutions using intuition and develop the thought process behind them. No hard prerequisites.

September 19, 2021 | 09:30 (EST) 19:00 (IST)

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Induction and other ideas by Abhay Bestrapalli

We explored the use of induction in combinatorics questions among other important ideas. We also go over instructive olympiad questions related to these. No hard prerequisites.

September 18, 2021 | 09:30 (EST) 19:00 (IST)

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The Hydra, Cyber Crime, and What We Know We Don't Know by Dia Basak

The talk discusses the "Hydra" theorem of Kirby and Paris and its unprovability from Peano arithmetic (which will be explained). It'll be helpful if people have seen things like formal proof and induction before, but there aren't any hard prerequisites.

September 12, 2021 | 08:30 (EST) 18:00 (IST)

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Functional Equations by Ananya Ranade

We discussed various techniques of solving functional equations and a few interesting problems. Techniques like substitution, equating, and canceling things to make equations easier will be discussed. We solve olympiad questions alongside

September 11, 2021 | 05:30 (EST) 15:00 (IST)

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Polynomials on R[X] Part 2 by Kazi Aryan Amin

We discussed properties and results relating to polynomials with real coefficients alongside interesting olympiad problems. We venture into polynomials with complex coefficients. There are no hard prerequisites except basic comfort with complex numbers and the definition of polynomials.

September 05, 2021 | 09:30 (EST) 19:00 (IST)

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Polynomials on R[X] Part 1 by Kazi Aryan Amin

We discussed properties and results relating to polynomials with real coefficients along with interesting olympiad problems. We venture into polynomials with complex coefficients. There are no hard prerequisites except basic comfort with complex numbers and the definition of polynomials.

September 04, 2021 | 09:30 (EST) 19:00 (IST)

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Introduction to Graph Theory by Pranjal Srivastava

This session was a brief introduction to graph theory in math olympiads. There are no hard prerequisites.

August 29, 2021 | 09:30 (EST) 19:00 (IST)

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Intro to Commutative Rings and Ideals by Rohan Goyal

We introduced commutative rings and ideals and further discussed special types of ideals such as prime ideals, maximal ideals, and domains like EDs, and PIDs, UFDs. Bonus points for knowing full forms. The prerequisites are the definitions of fields and rings.

August 28, 2021 | 09:30 (EST) 19:00 (IST)

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Group Theory Problem solving session by Arindam Bhattacharyya

We solve some problems (only up to section 4 in the handout) involving Lagrange theorem and number theoretic ideas and if time allows, motivate normal subgroups. The prerequisites are the first 3 sections of the handout or the respective recordings where the same content was covered.

August 15, 2021 | 09:30 (EST) 19:00 (IST)

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Group Theory Revision Session by Arindam Bhattacharyya

This was a revision session on group theory for a problem-solving session. It is a 30 min preclass session.

August 15, 2021 | 09:30 (EST) 19:00 (IST)

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Inversion by Atharva Parulekar

The session introduced inversion from the basics and goes over a few important lemmas and facts that will help us solve olympiad questions. We also solved olympiad problems where inversion is helpful. No hard prerequisites.

August 14, 2021 | 09:30 (EST) 19:00 (IST)

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Construction and Architecture by Rohan Goyal

We look at common ideas in construction-related problems in NT and Combinatorics. We also try to understand how to think of various types of constructions philosophically. No hard prerequisites.

July 31, 2021 | 03:30 (EST) 13:00 (IST)

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Miquel, Simson and Steiner by Sudharshan KV

We covered some properties of Miquel points, Simson and Steiner lines and solve some problems along the way. No hard prerequisites.

July 25, 2021 | 09:30 (EST) 19:00 (IST)

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Problem Solving Session 2.0 by Abhay Bestrapalli

We will help you solve various problems that we think are instructive. Specifically, IMO 2021 Q1, IMO 2021 Q5, and a problem from Russia 2004 are solved. No prerequisites. The whiteboard can be found in the youtube description

July 24, 2021 | 09:30 (EST) 19:00 (IST)

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Exponents in Number Theory by Tejas Mittal

We go through some basic techniques in solving olympiad problems, mostly concerning exponents of primes, like orders and the Lifting the Exponent lemma. The prerequisites roughly include Modular arithmetic and (up to) Euler's theorem. The used notes can be found in the Youtube description.

July 15, 2021 | 09:30 (EST) 19:00 (IST)

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Projective Geometry 2.0 by Ojas Mittal

We defined and characterized maps called projective transformations, and proved that maps sending lines to lines preserve cross ratio. This is a continuation of the previous session but section 1.1 of https://math.mit.edu/~notzeb/cross.pdf can be read as alternative prerequisites.

July 13, 2021 | 09:30 (EST) 19:00 (IST)

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Projective Geometry by Ojas Mittal

It focused on an introduction to projective geometry where we will discuss maps on the projective plane that sends lines to lines. Knowledge of basic linear algebra is suggested but not required

July 07, 2021 | 09:30 (EST) 19:00 (IST)

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ELMO Day 2 Livesolve

This is a ELMO Day 1 Livesolve by Kazi Aryan Amin and Abhay Bestrapalli. We tried to solve the questions from the olympiad(and got q4 and q5). You can find more about ELMO on aops.

July 01, 2021 | 08:30 (EST) 18:00 (IST)

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ELMO Day 1 Livesolve

This is a ELMO Day 1 Livesolve by Kazi Aryan Amin and Abhay Bestrapalli. We tried to solve the questions from the olympiad(and got all 3). You can find more about ELMO on aops.

June 29, 2021 | 08:30 (EST) 18:00 (IST)

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Hall's Theorem by Pranjal Srivastava

Hall's perfect matching theorem, a graph theoretic result about perfect matchings, often appears unexpectedly in a lot of olympiad problems. In this session, we'll first prove Hall's theorem, and then solve a few questions using it. No hard prerequisites.

June 27, 2021 | 09:30 (EST) 19:00 (IST)

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Combinatorial Game Theory 2.0 by Ritam Nag

A continuation of the discussion on combinatorial games from the prequel. We talk about games as a formal construct, the Sprague-Grundy theorem, Hackenbush and surreal numbers. The session shows you how to create ordinal numbers as games.

June 26, 2021 | 09:30 (EST) 19:00 (IST)

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Angle Chasing by Rohan Goyal

It covers the basics of angle chasing and power of point to solve olympiad geometry problems and prove various theorems. No prerequisites.

June 21, 2021 | 09:30 (EST) 19:00 (IST)

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Group Theory 2.0 by Arindam Bhattacharyya

We will prove Lagrange's theorem and introduce the notion of normal subgroups and end with isomorphism theorems. There is no Youtube recording for this session, but one may use the handout.

June 20, 2021 | 09:30 (EST) 19:00 (IST)

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Russian Problems by Kazi Aryan Amin

This session will cover combinatorics questions often called "Russian problems", which are characterized by low-tech, slick solutions, elegant statements, and seemingly random constants. There are no prerequisites. Extra pset in Youtube description.

June 13, 2021 | 09:30 (EST) 19:00 (IST)

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Functional Equations by Aayam Mathur

The session will be an introduction to methods and ideas in solving classic functional equations. Things will be covered from the basics with heavier emphasis on ideas and motivation rather than details.

June 12, 2021 | 09:30 (EST) 19:00 (IST)

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Complex Numbers in Geometry by Arnav Pati

The session introduces complex bashing and using complex numbers in geometry. There are no prerequisites.

June 06, 2021 | 09:30 (EST) 19:00 (IST)

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Combinatorics Problem Solving Session by Abhay Bestrapalli

The session goes over a bunch of olympiad questions that are instructive along with many ideas and techniques alongside. Specifically, ISL 2015 C1, TSTST 2016/5 and USAMO 2020/2 are solved.

June 05, 2021 | 09:30 (EST) 19:00 (IST)

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Angle Chasing with Conics 2.0 by Pranjal Srivastava

The session mainly focuses on properties of inconics of quadrilaterals, and will also contain some olympiad geometry that can be solved using conics. This is a continuation of the session by Rohan Goyal

May 30, 2021 | 09:30 (EST) 19:00 (IST)

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Combinatorial Game Theory by Ritam Nag

The video discusses tools and techniques for working with combinatorial games. There are no prerequisites.

May 29, 2021 | 09:30 (EST) 19:00 (IST)

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An Introduction to Group Theory by Arindam Bhattacharyya

The session introduces groups through many examples. It goes over various theorems like Lagrange and FLT.

May 23, 2021 | 09:30 (EST) 19:00 (IST)

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Angle chasing with conics by Rohan Goyal

The lecture introduced conics and various properties they exhibit. The lecture aimed to be accessible to everyone and thus no prerequisites except basic angle chasing are assumed but the results should be of interest to the experienced viewers as well.

May 22, 2021 | 09:30 (EST) 19:00 (IST)

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Max-flow Min-cut theorem by Aatman Supkar

This session was about the Max-flow Min-cut theorem and a discussion about flow in general.

May 16, 2021 | 09:30 (EST) 19:00 (IST)

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An Introduction to Graph Theory by Abhay Bestrapalli

This session was an introduction to graph theory for math olympiads. The session introduces graph theory from scratch and goes on to harder problems.

May 15, 2021 | 09:30 (EST) 19:00 (IST)

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Algorithms and Processes by Abhay Bestrapalli

The session is on analyzing algorithms in math olympiads and went through multiple ideas that lets us do this. It also covers further uses of algorithms. A Pset can be found in the Youtube description.

May 09, 2021 | 09:30 (EST) 19:00 (IST)

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