Math 3140
Abstract Algebra I


Fall 2019


Please see below for lecture summaries, homework and other study material.

Date Topics
Aug.26. Definition of groups. Groups from sets of numbers.
Aug.28. Groups from modular arithmetic and linear algebra. First properties of groups. Homework 1
Aug.30. Abelian groups. Orders and multiplication tables of groups. Symmetric groups.
Sep.02. Labor day; no class.
Sep.04. Notation for permutations. First properties of symmetric groups. Homework 2
Sep.06. Generating sets of symmetric groups.
Sep.09. Signs of permutations (via linear algebra). Dihedral groups.
Sep.11. More on dihedral groups. Symmetries of the tetrahedron. Homework 3
Sep.13. Subgroups.
Sep.16. Subgroups generated by subets of groups. Orders of elements in groups.
Sep.18. Orders in symmetric groups. Orders of elements vs orders of subgroups. Homework 4
Sep.20. Cosets of subgroups. Lagrange's Theorem.
Sep.23. Fermat's Little Theorem. Conjugation.
Sep.25. Properties of conjugation. Conjugation in the symmetric group. Homework 5
Sep.27. Normal subgroups.
Sep.30. Examples and properties of isomorphisms.
Oct.02. Examples and non-examples of homomorphisms. Homework 6
Oct.04. Properties of homomorphisms.
Oct.07. The first isomorphism theorem.
Oct.09. Applications of the first isomorphism theorem. Homework 7
Oct.11. Review for midterm exam.
Oct.14. Midterm.
Oct.16. The correspondence theorem. Direct products. Homework 8
Oct.18. Orders of elements in direct products. Internal direct products.
Oct.21. Group actions: definition and examples.
Oct.23. The homomorphism associated to a group action. Cayley's theorem. Homework 9
Oct.25. Orbits and stabilizers.
Oct.28. Class cancelled due to inclement weather.
Oct.30. Class cancelled due to inclement weather. No homework this week.
Nov.01. The orbit-stabilizer theorem. Counting the size of an orbit.
Nov.04. Burnside's (orbit-counting) lemma. Counting orbits.
Nov.06. More counting problems. Homework 10
Nov.08. The class equation and Cauchy's theorem.
Nov.11. Statements and an application of the Sylow theorems. Preparatory lemmas.
Nov.13. Proof of the Sylow theorems. Homework 11
Nov.15. Simple groups. Non-simplicity proofs using Sylow theorems.
Nov.18. Finitely generated abelian groups. Invariant and elementary factors.
Nov.20. Applications of the fundamental theorem of finitely generated abelian groups. Homework 12
Nov.22. Smith normal forms.
Dec.02. Definition and examples of rings.
Dec.04. Subrings, ideals, and ring homormorphisms. Homework 13
Dec.06. Quotient rings. Isomorphism theorems for rings. A construction of the complex field.
Dec.09. Review for final exam, I.
Dec.09. Review for final exam, II.