8 and 15 November, 2017
Speaker: Monalisa Dutta.
Title: Bézout's theorem.
Abstract: Bezout's theorem concerns with counting the number of points at which two curves intersect. This will be a two part talk. In the first part, algebraic preliminaries required to state and prove Bezout's theorem will be introduced.
25 October and 1 November, 2017
Speaker: Sanjoy Chatterjee.
Title: The Jordan canonical form.
Abstract: When an operator on a finite-dimensional complex inner product space is not diagonalizable, the next best thing that one can hope for is a Jordan canonical form. We will define a Jordan canonical form and show that the matrix of every operator on a finite-dimensional complex inner product space is similar to a Jordan canonical form in some basis.
11 and 18 October, 2017
Speaker: Sachchidanand Prasad.
Title: The inverse and implicit function theorems.
Abstract: The inverse function theorem lists sufficient local conditions on a vector-valued multivariable function to conclude that it is a local diffeomorphism. We will prove the inverse function theorem and use it to prove the implicit function theorem for multi-dimensional real euclidean spaces. We will closely look at the inverse function theorem in one dimension and a holomorphic version of it in the complex field. Finally, we will define regular values and show that the special linear group of degree n over the real field is a submanifold of general linear group of degree n over the real field.
4 October, 2017
Speaker: Sanjoy Chatterjee.
Title: Topological properties of the orthogonal matrix group and the unitary matrix group.
Abstract: We will show that the orthogonal matrix group and the unitary matrix group are compact spaces. We will also show that the unitary matrix group is a connected space. Finally, we will look at the connected components of the orthogonal matrix group.
27 September, 2017
Puja vacation.
20 September, 2017
Midsemester examinations.
6 and 13 September, 2017
Speaker: Nurun Nesha.
Title: Rademacher's theorem.
Abstract: Rademacher's theorem states that if a function from an open set of n-dimensional real space into the reals is almost everywhere differentiable in that open set. We will first prove the case for 1-dimensional real space and then we will prove the general case.
30 August, 2017
Speaker: Monalisa Dutta.
Title: Hilbert's Nullstellensatz.
Abstract: Hilbert's Nullstellensatz establishes a fundamental relationship between geometry and algebra. In its simplest form, it states that any maximal ideal in a polynomial ring in n-many variables over an algebraically closed field is generated by n-many polynomials of degree one. We will also show that this statement is equivalent to the fact that any family of polynomials in this polynomial ring, whose generating ideal is not the whole ring, has a common zero. We will further show, using a method called "Rabinowitsch trick ", how Hilbert's Nullstellensatz relates "algebraic sets" to ideals in polynomial rings over algebraically closed fields. Here, the concept of an "algebraic set" will be defined in the talk. We finish with some concrete applications of the ideas developed.
16 and 23 August, 2017
Speaker: Chandrahas Piduri.
Title: CW Complexes.
Absract: CW complexes will be introduced with examples. In the second talk, products of CW complexes will be discussed. We will also show that CW complexes are normal spaces.