Groups, Rings, and Fields


Math 620
Fall 2022
Meeting Tu, Th. 11:00-12:15
GMCS 405
San Diego State University
Last class: Thurs. Dec 8.
Final Exam: Thurs. Dec. 15, 10:30 - 12:30.


Professor: Mike O'Sullivan
Web page: http://mosullivan.sdsu.edu
Email: mosullivan@sdsu.edu
Office: GMCS #582
Office Hours: Tu Th, 10-10:30, 1:30-2:45. Mo 11:00-3:00
You may make an appointment for another time, or just stop by my office. If I am in and available, we can talk.

Detailed Information

SCHEDULE
ASSIGNMENTS

Course Description

We will study the core objects in abstract algebra: groups, rings and fields. The term ``abstract'' highlights the approach to mathematics that emerged in the 20th century in which there was less reference to ``real objects'' and a greater emphasis on proving theorems from a small set of simple axioms. For example, the symmetries of a 3-dimensional object tell you something about the nature of the object. But, symmetry itself is interesting. Symmetries of an object can be composed (apply one then another) and produce another symmetry. Each symmetry has an inverse, which undoes the given symmetry. Abstractly, one can consider the properties of a set (e.g. symmetries) with an operation (e.g. composition) and an inverse to the operation. We call such an object a group. Discovering the structure and properties of abstracts groups was a massive project in the last century.

Ring theory evolves from recognizing that the basic properties of the integers (from grade school!)---two operations ($+, *$), with commutativity, associativity, distributivity---extend to polynomials and can be extended further to abstractly defined objects. Similarly, the properties of the rational numbers (now every nonzero element has a multiplicative inverse) can be considered in an abstract axiomatic way. This is the area called field theory.

I love this material because it gives a deeper and richer understanding of school mathematics, but also unveils a world of very complex and intricate beauty.


Resources


Prerequisites

Some experience with abstract algebra: group theory, ring theory, or number theory. If you have just studied one of these topics be prepared (allot time!) to work a bit harder in the new topics.

Primary Topics

Some of the following topics will be familiar from your undergraduate course. We will cover them in greater depth, and with more attention to details. I expect this material to take 9 weeks.