Spring 2000
Math 841: Geometry of Linear Algebraic Groups


Instructor: Frank Sottile
Office: Van Vleck 413
Telephone: 262 - 3545
email: sottile@math.wisc.edu
WWW: http://www.math.wisc.edu/~sottile
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Office Hours: By appointment.
Lectures: Tu, Th 2:30 - 3:45, B135 van Vleck.
Prerequisites: Knowledge of undergraduate algebra; willingness to learn/believe selected results from other fields.
Books: The course will have no textbook. However, I plan to reserve a number of books in the library, and I will have several others (including Borel and Humphreys) in my office, or at home and available for short-term loan.
Books on reserve at the library:
Borel, Linear Algebraic Groups.
Humphreys, Linear Algebraic Groups.
Shafarevich, Basic Algebraic Geometry.
Fulton, Young Tableaux.
Fulton & Harris, Representation Theory.
Atiyah & Macdonald, Introduction to Commutative Algebra.
Other books I have at home
Overview
Course Particulars The only requirements for this course will be class participation.
No class on 15 February - I will be out of town.
I might make up for this by hosting an evening lecture or problem session.
Topics I intend to cover
Notes from some Lectures notes01,     notes02,     notes03,     notes04,     notes05,     notes06.     notes07 (draft version).     notes08 (draft version).     notes09 (draft version).
Course webpage http://www.math.wisc.edu/~sottile/courses/841.html

Overview

Linear algebraic groups, which include the familiar general linear groups, as well as the symplectic and orthogonal groups, are classic mathematical objects that are important in many areas of mathematics. These areas include representation theory, finite groups, linear algebra, mathematical physics, linear systems theory, differential geometry, algebraic topology, algebraic geometry, and combinatorics.

This introductory course will develop some elementary theory of linear algebraic groups, and then use this to study the geometry of their associated flag manifolds. We will concentrate on their important Schubert subvarieties, cohomology rings of the complex flag manifolds, and also the interesting Schubert polynomials, which represent classes of Schubert varieties in these cohomology rings. Our goal will be the Schubert calculus, which describes the combinatorics and algebra of the multiplication of these Schubert classes, and ultimately intersections of Schubert varieties.

This is an area of active mathematical research, with recent contributions by members of our department, including Arun Ram. We hope to present some recent results in the Schubert calculus and discuss some open problems or possible directions for further research. The course will touch on combinatorics, representation theory, algebraic geometry, and algebra, and will also give an introduction to some interactions of these subjects in the Schubert calculus.


Topics I intend to cover

Minimal introduction to algebraic geometry.
                    Affine Varieties, regular functions, Algebraic-Geometric Dictionary
Affine Algebraic Groups
                    Definitions, examples
                    Connected components
                    Linearization of affine algebraic groups
                    Action of algebraic groups on varieties
                    Homogeneous spaces
                    Borel fixed point theorem
                    Structure and classification of semisimple reductive groups
                    Bruhat decomposition
Enumerative geometry and cohomology of G/P
                    Schubert cellular decomposition of G/P
                    Ehresmann picture of cohomology
                    Borel picture of cohomology
                    General Giambelli, Pieri, and Littlewood-Richardson problem in cohomology
The Grassmannian
                    Explicit cellular decomposition
                    Giambelli formula
                    Pieri formula
                    Littlewood-Richardson formula
                    Formulation of enumerative geometry as systems of equations
Classical flag manifold
                    Cellular decomposition
                    Construction of Schubert polynomials
                    Pieri-type formula


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Last modified: 28 January 2000 by Frank Sottile