Math 81/111 Abstract Algebra


Require textbook (referred to as DF):

  • David S. Dummit and Richard M. Foote, Abstract Algebra, 3rd Edition

List of other useful texts and resources:

  • J. S. Milne, Fields and Galois Theory, (referred to as FT) available online via Milne's website
  • Juliusz BrzeziƄski, Galois theory through exercises, available on-line via SpringerLink
  • Keith Conrad's expository notes
  • Serge Lang, Algebra, Graduate Texts in Mathematics, vol. 211, Third edition, 2005.
  • Ian Stewart, Galois Theory, Third edition, 2003.

Weekly problem sets will be due in class on Friday.

Weekly Syllabus and Homework

Updated March 01, 2024.

Week Date Topics Reading Homework
1 Wed 03 Jan History of solving polynomial equations. The complex numbers and complex conjugation.
Fri 05 Jan Field Extensions. Ring theory reminders. Irreducible polynomials and ideals in polynomial rings. DF 9.2
FT 7-11
2 Mon 08 Jan Roots. Fundamental Theorem of Arithmetic. Reduction mod p. Irreducibility criteria for polynomials. Irreducible polynomials over finite fields. Eisenstein's criterion. DF 9.2-9.5
FT 11-14
Problem Set #1
Wed 10 Jan Finitely generated extensions. Simple extensions. Classification of simple extensions. DF 13.1
FT 16-18
Fri 12 Jan Gauss's Lemma and primitive polynomials. Transcendental and algebraic elements. Minimal polynomial. DF 9.1, 13.2
FT 11-13, 18-21
3 Mon 15 Jan No class: Martin Luther King, Jr. Day Problem Set #2
Wed 17 Jan Tower law for degrees. Algebraic extensions, continued. DF 13.2
FT 14-15, 19-20
Thu 18 Jan X-hour lecture: Compass and straightedge constructions. Constructible numbers form a field. DF 13.3
FT 22-24
Fri 19 Jan Quadratic closure. Construction impossibility proofs. DF 13.3
FT 22-24
4 Mon 22 Jan Splitting fields. DF 13.4
FT 28-29
Problem Set #3
Wed 24 Jan Separability. DF 13.5
FT 31-33
Thu 25 Jan X-hour lecture: Algebraic closure. DF 13.4
FT 25-26, 87-90
Fri 26 Jan Frobenius. Perfect fields. Finite fields. DF 13.5
FT 27-33
5 Mon 29 Jan Embeddings. Field automorphisms. Automorphism group. Constructing automorphisms. Automorphism group calculations. Fixed fields. DF 14.1
FT 27-28, 36-39
Problem Set #4
Wed 31 Jan Galois extensions. Linear independence of embeddings. DF 14.1-14.2
FT 36-37
Fri 02 Feb Fundamental theorem of Galois theory. Examples of the Galois correspondence. DF 14.2
FT 36-39
6 Mon 05 Feb Proof of the Galois correspondence. DF 14.2
FT 38-41
Problem Set #5
Wed 07 Feb Proof of the Galois correspondence (continued). Galois group of a polynomial. Normal subgroups of the Galois group. DF 14.2
FT 35-45
Fri 09 Feb Normality. Normal closure. Galois is normal and separable. DF 14.2
FT 35-43
7 Mon 12 Feb Primitive element theorem (algorithmic and set-theoretic). DF 14.4
FT 61-63
Takehome Midterm Exam
Wed 14 Feb Cyclotomic fields. Galois theory of finite fields. DF 13.6, 14.3, 14.5
FT 64-67, 53-55
Fri 16 Feb No class!
8 Mon 19 Feb Radical extensions. Solvability by radicals. DF 14.7
FT 45-46, 76-77
Problem Set #6
Wed 21 Feb Solvability by radicals. Galois's solvability theorem. DF 14.7
FT 45-46, 76-77
Thu 25 Jan X-hour lecture: Discriminant. Galois perspective on quadratic and cubic extensions. DF 14.6
FT 47-49
Fri 23 Feb Quartic extensions and the cubic resolvent. DF 14.7
FT 49-52
9 Mon 26 Feb Quartic extensions. DF 14.7
FT 49-52
Problem Set #7
Wed 28 Feb Computational algebra. LMFDB.
Fri 01 Mar Infinite Galois theory. Krull topology. Profinite groups. DF 650-652
FT 91-96
10 Mon 04 Mar Infinite Galois theory. Looking ahead! DF 650-652
FT 91-96
Final Exam Review
Fri 08 Mar Final Exam!



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