Math 171: Abstract Algebra

Fall 2019


Topics in group theory include groups, subgroups, quotient groups, Lagrange's theorem, symmetry groups, and the isomorphism theorems. Topics in Ring theory include Euclidean domains, PIDs, UFDs, fields, polynomial rings, ideal theory, and the isomorphism theorems. In recent years, additional topics have included the Sylow theorems, group actions, modules, representations, and introductory category theory.


Dagan Karp
Office: 3414 Shan
Office hours: Mon/Thu 4-5pm, and open door.


This course will meet for lectures Tuesday and Thursday, 2:45-4:00pm in Shanahan 3421.


We'll use Abstract Algebra: An Introductory Course, by Gregory T. Lee.
It is freely available online through the Claremont Colleges Library.


There will be two exams and weekly homework. Let A be your homework average, B your score on Exam 1, C = Exam 2, D = Max (A,B,C) and Then your grade will be determined by


Written homework will be due each Friday at 5:00pm at my office, and is posted below.

You are encouraged to discuss the homework with other members of the class, and it is appropriate to acknowledge the assistance of others. You will, however, be expected to write up your solutions on your own. The instructor will reserve the right to refuse to accept late homework for any reason. Graded homework, however, may (in most cases) be rewritten and submitted at a later date. Please consult the HMC mathematics homework format guidelines for helpful tips on homework submission and formatting.


Like other writing, good math writing is a process that includes revision. In Math 171 this is reflected in the rewrite policy. You will have the opportunity to turn in a rewritten copy of every homework assignment.
For details, see the Math 171 Rewrite Policy.


Elisha Dayag and Hanna Hoffman are our graders and tutors. They will hold tutoring hours Thursday and Sunday 7:00-9:00pm in Shan 2430.


There will be two exams, both of which are take-home. Exam 1 will be distributed Thursday, 10/3 and due 10/10. Exam 2 will be distributed Thursday, 12/12, due Wednesday 12/18.

Critical Readings

In addition to the written homework, suggested readings will be posted on the homework page in conjunction with upcoming lectures. Before each lecture, read the corresponding material. Class activities will depend on your study of this material in advance (which is a departure from most lower division courses).

The goals of the critical reading exercises are manifold: to better the student's independent intake of mathematical exposition, to train in independent learning, to increase the interactive nature of the course (by allowing the instructor to respond to questions and comments), and to make the course more tailored to the specific curiosities of the class as a whole.


Students interested in using LaTeX are encouraged to do so, but it is not required.


It is the policy of The Claremont Colleges to accommodate students with temporary or permanent disabilities. Any student with a documented disability who requires reasonable accommodations should contact Brandon Ice, Coordinator for Student Disability Resources at (909) 607-3148 or, as soon as possible. Students from the other Claremont Colleges should contact their home college's disability officer. Counterparts at the other campuses are as follows: CMC: Julia Easley ( CGU: Chris Bass ( HMC: Deborah Kahn ( Pitzer: Gabriella Tempestoso ( Pomona: Jan Collins-Eaglin ( Scripps: Leslie Schnyder (

Math is for all

My goal is to welcome everyone to mathematics, and to broaden participation in the mathematical sciences. Our classroom should be an inclusive space, where ideas, questions, and misconceptions can be discussed with respect. There is usually more than one way to see and solve a problem and we will all be richer if we can be open to multiple paths to knowledge. I look forward to getting to know you all, as individuals and as a learning community.

Lecture Notes

Here are (old) course notes.
  1. Introduction to groups: symmetry and permutation
  2. Formal definition of group, first examples and properties
  3. Subgroups
  4. Cyclic Groups
  5. Symmetric and Dihedral Groups
  6. Cosets and Lagrange's Theorem
  7. Group Homomorphisms
  8. Normal Subgroups
  9. Isomorphism Theorems
  10. The Fundamental Theorem of Finitely Generated Abelian Groups
  11. Definition of Ring, first examples and properties
  12. Ring homomorphisms, subrings, and quotient rings
  13. Polynomial rings, matrix rings and group rings
  14. Ideals
  15. Maximal and Prime Ideals
  16. Euclidean Domains
  17. Principal Ideal Domains
  18. Unique Factorization Domains
  19. Polynomial Rings Revisited
  20. Introduction to Category Theory: Objects and Morphisms
  21. Functors

Homework and Readings
    HW 2. Due Thu Sep 19.
    Reading: 3.4 (worth rereading) and 3.5
    Problems: 3.14, 3.15, 3.16, 3.17, 3.18, 3.21
    HW 3. Due Friday, Sep 27.
    Reading: 3.5 and 3.6
    Problems: 3.33 (1) and (3), 3.37, 3.38, 3.43, 3.47, 3.52.
    Rewrite: HW 1
    HW 4. Due Friday, Oct 4.
    Reading: 3.7, 4.1
    Problems: 3.53 (1), 3.54 (2) (feel free to use cycle notation), 3.55, 3.56.
    Rewrite: HW 2
    Exam 1
    Out: Thursday, October 3
    Due: Thursday, October 10
    HW 5. Due Friday, October 18.
    Reading 4.2-4.4
    Problems: 4.1, 4.7, 4.12, 4.18, 4.24, 4.30
    Rewrite: HW3
    HW 6. Due Friday, October 25.
    Reading: 4.5, 4.5, Chapter 5
    Problems: 4.37, 4.42, 4.50
    Rewrite: HW 4
    HW 7. Due Friday, November 1.
    Reading: 8.1-8.4
    Problems: 5.1, 5.2, 5.3, 5.12, 5.15, 5.20
    Rewrite: HW 5
    No class Thursday, November 7.
    HW 8. Due Friday, November 8.
    Reading: 9.1-9.4
    Problems: 8.2, 8.5, 8.16, 8.23, 8.30, 8.31.
    Rewrite: HW 6
    HW 9. Due Friday, Nobember 15.
    Reading: 9.5, 9.6, 10.1
    Problems: 9.2, 9.6, 9.8, 9.11, 9.14, 9.31.
    Rewrite: HW 7
    HW 10. Due Friday, November 22.
    Reading: 10.2
    Problems: 9.32, 9.36, 9.43, 9.44, 10.2, 10.6.
    Rewrite: HW 8
    No class Thursday, November 28 and no HW Friday, November 29.
    HW 11. Due Friday, December 6.
    Reading: 10.3
    Problems: 10.4, 10.5, 10.11, 10.19.
    Rewrite: HW 9
    HW 12. Due Friday, December 13
    Reading: None.
    Problems: Write a very brief essay, of no more than 250 words, describing your personal understanding of a topic you've learned in Math 171 in a non-technical way. The goal isn't to give a precise definition or statement of a theorem, but rather how you yourself think of the topic, perhaps by analogy with things in your life experience. For example, imagine you are talking to an audience of high school students. This should be typed.
    Rewrite: None.