Meeting 20 : Thu, Feb 23, 04:00 pm-04:50 pm References Exercises Reading
Sets, Relations, Domain, Codomain, Functions, Partial Functions, One-one, Onto, Image, Pre-image, Bijection Examples. Representing functions using graphs. Notion of cardinality of sets.
Meeting 21 : Mon, Feb 27, 09:00 am-09:50 am References Exercises Reading
Review of Cardinality. Notion of infinities. Cardinality of infinite sets. Deceiving examples. Cardinality of even numbers, Odd numbers equal to Natural numbers.
Meeting 22 : Tue, Feb 28, 08:00 pm-08:50 pm References Exercises Reading
Countable and countably infinite sets. Any infinite subset of N has the same cardinality as N, using well ordering principle. Proof of well-ordering principle using mathematical induction.
Meeting 23 : Wed, Mar 01, 01:00pm-01:50pm References Exercises Reading
A is a subset of B. If B is countable then A must be countable. In search of bigger infinities. Cardinality of NxN is same as N. Composition of Injections.
Meeting 24 : Mon, Mar 06, 09:00 am-09:50 am References Exercises Reading
If A,B are countable, then A union B is countable and AxB is countable. Conclude that Z, Q are countable sets.
Meeting 25 : Tue, Mar 07, 08:00 pm-08:50 pm References Exercises Reading
Uncountability. Cantor's diagonalization. More examples of uncountable sets.
Meeting 26 : Wed, Mar 08, 06:00 am-06:00 am References Exercises Reading
Diagonalization in set form - there cannot be an surjection from a set to its power set. Infinitely many types of infinities. Equivalent definitions of countability.
Meeting 27 : Thu, Mar 09, 04:00 pm-05:00 pm References Exercises Reading
Counting & Finite Sets. Product rules, Sum rule, Permutation and Combinations.
Meeting 28 : Tue, Mar 14, 08:00 am-08:50 am References Exercises Reading
Combinatorial identities. Double counting. Examples.
Meeting 29 : Wed, Mar 15, 01:00pm-01:50pm References Exercises Reading
Proof by Bijections. Number of even sized subsets and number of odd sized subsets are equal. Formal proof of bijectivity. Associated Binomial identity.
Meeting 30 : Thu, Mar 16, 04:00 pm-04:50 pm References Exercises Reading
Number of paths (which use only east and south edges from a point) of a grid from top left to bottom-right corner of an nxn grid. Problem of counting the number of diagonal avoiding paths. The bijection from number of balanced paranthesis to diagonal avoiding paths.
Meeting 31 : Mon, Mar 20, 04:00 pm-05:00 pm References Exercises Reading
Catalan Number and the proof by Bijection.
Multi-choosing and associated bijections.
Meeting 32 : Wed, Mar 22, 01:00pm-01:50pm References Exercises Reading
More on Combinatorial Identities. Principle of Inclusion-Exclusion. Derangements.
Meeting 33 : Thu, Mar 23, 04:00 pm-04:50 pm References Exercises Reading
Pigeon Hole Principle and generalizations. Proof and a few simple applications.
Meeting 34 : Mon, Mar 27, 09:00 am-09:50 am References Exercises Reading
More Applications of PHP. Erdos-Szekeres Subsequence Theorem.
Meeting 35 : Mon, Mar 27, 04:00 pm-05:00 pm References Exercises Reading
More on PHP. Dirichlet's Approximation principles for irrational numbers.
Meeting 36 : Wed, Mar 29, 01:00pm-01:50pm References Exercises Reading
Principle of inclusion exclusion. Example of "prime looking numbers" General formulation and proof of the principle using combinatorial arguments. An application. Derangements. Formulation as a PIE problem.
Meeting 37 : Thu, Mar 30, 04:00 pm-04:50 pm References Exercises Reading
Counting the number of derangements using inclusion-exclusion principle.
Formulating Counting problems as recurrences.
Meeting 38 : Mon, Apr 03, 09:00 am-09:50 am References Exercises Reading
Solving Recurrences. Linear Homogeneous Recurrences with constant coefficients. Characterestic equation. Case when the characterestic equation has distinct roots.
Meeting 39 : Mon, Apr 03, 04:00 pm-05:00 pm References Exercises Reading
Case when the characterestic equation has repeated roots.
Meeting 40 : Tue, Apr 04, 08:00 pm-08:50 pm References Exercises Reading
Linear Non-homogeoneous Recurrence relations with constant coefficients. Particular solution. Solution to homogeneous part.
Meeting 41 : Mon, Apr 10, 04:00 pm-05:00 pm References Exercises Reading
Generating functions. Examples. Solving recurrences using generating functions.
Solving Derangements using recurrence relations.