9/21/2008  1. Introduction to the Math circle. 2. Lecture: Mathematics of Color (Olga Radko) (Boelter Hall 3400) 3. Presenting solutions of the Welcome problem set Handouts: Solutions: Geometry  Solutions: Algebra  Welcome problem set: Geometry  Welcome problem set: Algebra 
9/28/2008  Group A (problemsolving techniques): MS6627
Group B (geometry): MS6221 Handouts: Group A (Parity)  Group B (Geometry of triangles) 
10/5/2008  Handouts: Group B (Geometry of Triangles)  Group A (Parity) 
10/12/2008  Group A: MS6201
Group B: MS6221 Handouts: Angles and Circles (group B)  Triangles (group B)  Divisibility (group A) 
10/19/2008  Group A (MS6201): Problems on Logic Group B (MS6221): Point Mass geometry and barycentric coordinates; Handouts: Point Mass Geometry  Logic 
10/26/2008  Pigeonhole principle:
We will motivate, prove and apply the Pigeonhole principle in a series of problems
Knots and Invariants:
In mathematics, a knot is a closed piece of string in threespace. Two
knots are equivalent if they can be deformed into each other. We will
explore several ways of showing that certain knots are not equivalent,
using invariants.
Handouts: Knots and Invariants  Pigeonhole principle 
11/2/2008  We will continue with the topics that we have started earlier;
Please solve the problems from the problem sets distributed last time at home. Handouts: Point Mass Geometry (II)  Point Mass Geometry (I) 
11/9/2008  Group A: We will solve a series of problems which can be easily attacked using trees, even if trees are not mentioned in the formulation of the problem.
Group B: Students will first present solutions of problems on barycentric coordinates.
Then, after reviewing the definition of the center of mass via vectors, we will prove (and apply) the theorems by Cheva and Menelaus. Handouts: Trees  Theorems by Cheva and Menelaus 
11/16/2008  Group A: We will take the first steps in learning the method of mathematical induction;
Group B: Any three noncollinear points always lie on some common circle, but in general it is rare for four points to have that property  unless one is trying to solve an Olympiad problem. Then, the observation that certain quadrilaterals are cyclic often turns out to be the key to the solution. We will survey some facts about cyclic quadrilaterals, and use them to solve actual Olympiad problems. Handouts: Cyclic quadrilaterals  Induction 
11/23/2008  Graphs: We will learn about simple properties of graphs through problemsolving.
Inversion: Inversion with respect to a circle is a spectacular geometric transformation of the plane that allows to solve some seemingly unapproachable problems. E.g., the following two problems posed by an ancient Greek mathematician Appolonius:
Using a compass and a ruler, construct a circle tangent to three given circles;
Given two fixed points on the plane, find the set of all points whose distance to the first fixed point is k times the distance to the other point.
Handouts: Inversion: workbook  Inversion: problem set 
11/30/2008  
12/7/2008  Group A: We will practice constructing inductive proves, and will also solve several problems related to graphs;
Group B: in MS 6627 We will discuss basic mathematical aspects of computer
games and movie special effects. Specifically, we will cover the
mathematical representations used for representing geometry of digital
characters and objects, clothing, fluids like water and smoke and a
few other examples. 
12/14/2008  We will have a small party after the end of the session!!! 
1/11/2009  Group A: This is the first of a series of meetings devoted to combinatorics. We will see how permutations and combinations arise naturally in a variety of problems.
Group B: We will review the basics of modular arithmetic and Euclidean algorithm in preparation for Unique factorization in exotic number systems presented by Jared Weinstein in a series of two future meetings. Handouts: Modular Arithmetic 
1/18/2009  Group A: We will continue solving problems involving permutations and permutations with repetitions;
Group B: We will solve many geometry problems from AMC 10/12 exam. Note that the review session will last 3 hours, 1  4 p.m. in MS 6627 . The session will include a practice AMC test. 
1/25/2009  Group A: Please read Chapter 1 of Introduction to Counting and Probability by D. Patrick in preparation for the session;
Group B: We will learn about quadratic residues. It is enough to know the basics of modular arithmetic (to the extent we covered on Jan. 11th meeting). Handouts: Quadratic residues 
2/1/2009  Group A: As homework for next Sunday, please read Sections 1.41.5 and 2.12.3 (as far as page 37) and do the following exercises:
1.4.4
1.5.1(a)(d), 1.5.3(a)(c)
2.2.2, 2.2.3
2.3.1, 2.3.4
Challenge: 1.34, 1.36, 2.28, 2.32
Group B: We will continue learning about quadratic residues and unique factorization for Gaussian integers and some other number systems. Handouts: Unique factorization in exotic number systems 
2/8/2009  
2/15/2009  
2/22/2009  Group B: We will learn to solve linear Diophantine equations in two variables.
Handouts: 
3/1/2009  Group A:
Please read sections 5.15.4 and solve
5.2.1, 5.2.2, 5.2.3
5.3.1, 5.3.3, 5.3.4
5.4.1
Challenge: 5.3.5, 5.18, 5.21 
3/8/2009  Group A homework:
Read Chapter 6.
5.4.3
Review 5.11, 5.13, 5.15
Challenge: 5.26, 6.14, 6.16, 6.19
Group B: this will be a problemsolving session devoted to AIME preparation. If you are not participating in AIME this year, I recommend attending, just to do the problemsolving. 
3/15/2009  Handouts: NonLinear Diophantine equations 
3/22/2009  
3/29/2009  
4/5/2009  Group A: Please work on problems 8.2.1, 8.2.2, 8.2.3, 8.2.5 for homework.
Handouts: Image processing slides  Image processing worksheets 
4/12/2009  Group A homework:
7.2.2, 7.2.3
7.3.1, 7.3.3, 7.3.4
7.4.1, 7.4.3, 7.4.6
Challenge: 7.22, 7.24

4/19/2009  Handouts: Public Key Cryptography  Probability and Independence 
4/26/2009  Group A: We'll be covering material related to chapters 89. Please read sections 8.28.4, and if you have time also take a look at 8.5, and perhaps a problem or two from chapter 9, which consists of a number of challenging problems. Since we've spent a few weeks going over the basics, this session will be about reviewing what we've learned and attempting some of these more challenging problems. I've included a number of problems below, with suggested numbers of problems per section of chapter 8. Here are some problems from the book: 8.2.2, 8.2.3, 8.3.1, 8.3.2, 8.3.4, 8.4.1, 8.4.3 From section 8.5: (If you get there) 8.5.1 Review: (If you'd like more practice) 8.17, 8.24 Challenge: (Try to solve at least one): 8.37, 9.8, 9.9, 9.10
Group B: Secret sharing refers to any method for distributing a secret amongst a group of participants, each of which is allocated a share of the secret. The secret can be reconstructed only when the shares are combined together; individual shares are of no use on their own. Secret sharing is an important primitive in several protocols for "secure multiparty computation (MPC)" (We will explore how mathematics and basic number theory can be used in cryptography to develop Secret Sharing schemes and Secure Multiparty Computation schemes. 
5/3/2009  Group A:
Please read sections 8.58.6, and 9.2, and work on the following homework problems:
8.5.3, 8.5.4
Review problems: 8.22, 8.27
Challenge: 9.11, 9.12 
5/10/2009  Group A:
Here are some HW problems:
10.2.2, 10.2.3
10.3.2, 10.3.4
11.2.1, 11.2.2
Challenge: 10.17, 10.21
Group B: What are finite fields? We'll answer this question and you'll see that you are already familiar with many of them, in a different guise. There are some nice applications that are easy to understand; we'll look at a few. 
5/17/2009  Group A: TBA
Group B: We will look at the Dirichlet product of arithmetic functions and the Mobius inversion formula. Special attention will be given to multiplicative functions. 
5/24/2009  Group B: Please go over the proof of the fact that Euler's function phi(n) is multiplicative in preparation for the meeting.
We will discover some properties of convolution; prove Mobius inversion formula (via convolution), and use all of these in problem solving. Handouts: Sumfunctions and convolution 
5/31/2009  
6/7/2009  Mathematical celebration:
 group B will be engaged in a Math Battle ;
 group A will have a Math Relays contest;
 Junior circle will enjoy playing several mathematical games.
These events will be followed by the awards ceremony for all the wonderful things the participants have done throughout the year and a party!
