Mathematics: Algebra

Winter Semester 2026


Basic Information

Lecturer: Joshua Maglione (joshua.maglione at universityofgalway.ie).

Lectures:

  • Tuesday at 10am (Anderson Theatre)
  • Thursday at 10am (AMB-1021)

Tutorials: Start on the 14th of September – more information on Canvas.

Assessment: Details of this are on Canvas.

Additional Materials:

  • Elementary Number Theory by G. A. Jones & J. M. Jones (1998). Available online through the Library.

Exercise Sheets

These exercise sheets are not marked. You do not need to turn them in. They will be covered in the tutorials.

Sheet 1    Solutions

Sheet 2    Solutions

Sheet 3    Solutions coming soon!


Sample Tests

First algebra test    Solutions coming soon!


Lecture Notes

Week 1

Lecture 01 : A brief (and unfinished) introduction to modular arithmetic

Lecture 02 : Divisibility and the Euclidean algorithm

Week 2

Lecture 03 : We solve linear Diophantine equations in two variables using Bézout’s theorem

Lecture 04 : More on linear Diophantine equations in two variables and starting modular arithmetic

Extra: Back-substition : Two examples and two exercises around back-substitution

Week 3

Lecture 05 : We show that (integer) congruence is an equivalence relation

Lecture 06 : We do some algebra on $\mathbb{Z}_m$

Week 4

Lecture 07 : We play with PPSNs and discuss multiplicative inverses

Lecture 08 : We discuss when multiplicative inverses exist and how to find them

Week 5

Lecture 09 : We solve general congruences and consider systems of congruences

Lecture 10 : We look at the Chinese Remainder Theorem and Fermat’s Little Theorem

Extra: Additional problems    Solutions : Practice problems from weeks 1–4

Week 6

Lecture 11 : We generalize Fermat’s little Theorem using Euler’s totient function