Math 215A, Algebraic Topology, Fall 2020


Course Control Number: 24846


Instructor: David Nadler

Office Hours: Fridays 3:30-4:30pm, zoom id: 936 2923 9224


GSI: German Stefanich

Office Hours: Fridays 11am-1pm, zoom id: 982 5809 2595


Lectures: Mondays and Wednesdays 3-4:30pm, zoom id: 941 2768 9910, passcode: 264259

Lectures will be a mix of traditional presentations and breakout sessions with group discussion.

Lecture notes:

  1. Lecture 1 (W 8/26/20)
  2. Lecture 2 (M 8/31/20)
  3. Lecture 3 (W 9/2/20)
  4. Lecture 4 (W 9/9/20)
  5. Lecture 5 (M 9/14/20)
  6. Lecture 6 (W 9/16/20)
  7. Lecture 7 (M 9/21/20)
  8. Lecture 8 (W 9/23/20)
  9. Lecture 9 (M 9/28/20)
  10. Lecture 10 (W 9/30/20)
  11. Lecture 11 (M 10/5/20)
  12. Lecture 12 (W 10/7/20)
  13. Lecture 13 (M 10/12/20)
  14. Lecture 14 (W 10/14/20)
  15. Lecture 15 (M 10/19/20)
  16. Lecture 16 (W 10/21/20)
  17. Lecture 17 (M 10/26/20)
  18. Lecture 18 (W 10/28/20)
  19. Lecture 19 (M 11/2/20)
  20. Lecture 20 (W 11/4/20)
  21. Lecture 21 (M 11/9/20)
  22. Lecture 22 (M 11/16/20)
  23. Lecture 23 (W 11/18/20)
  24. Lecture 24 (M 11/23/20)
  25. Lecture 25 (M 11/30/20)
  26. Lecture 26 (W 12/2/20)

Question? Try asking on Piazza.


Prerequisites: Familiarity with point-set topology and abstract algebra.


Primary source: A. Hatcher, Algebraic Topology, available here.


Syllabus: Fundamental group and covering spaces, simplicial and singular homology, cohomology and Poincare duality.

Roughly Chapters 0-3 of Hatcher's textbook, covered roughly as follows:


Evaluation: Each week there will be homework. There will also be two midterms and a final exam.

Midterm 1: during Week 6 (9/28-10/2); covering material through end of Week 4 (9/14-9/18).

Midterm 1

Midterm 1 solutions

Midterm 2: during Week 12 (11/9-11/16); covering material through end of Week 9 (10/26-10/30).

Midterm 2

Midterm 2 solutions

Grades will be determined by homework (20%), the midterms (20% each), and the final (40%).


Homework: Unless otherwise noted, problems are from Hatcher's textbook.

Homework is due each Monday at noon. Please submit assignments on Gradescope. Contact the GSI German with any questions.

  1. Due Monday 8/31/20: Ch. 0, Ex. 3, 6, 10, 14, 16, 18.
  2. Due Monday 9/7/20: Ch. 0, Ex. 19, 23; Ch. 1.1, Ex. 2, 3, 5, 6.
  3. Due Monday 9/14/20: Ch. 1.1, Ex. 8, 9, 10, 12, 13, 14.
  4. Due Monday 9/21/20: Ch. 1.1, Ex. 16, 18; Ch 1.2, Ex. 3, 4, 10, 14.
  5. Due Monday 9/28/20: Ch 1.2, Ex. 16, 21, 22; Ch 1.3, Ex. 4, 5, 7.
  6. Due Monday 10/5/20: Ch 1.3, Ex. 8, 10, 11, 14, 16, 18.
  7. Due Monday 10/12/20: Ch 1.3, Ex. 23, 32; Ch 1.B, Ex. 2; Ch 2.1, Ex. 2, 5, 9.
  8. Due Monday 10/19/20: Ch 2.1, Ex. 17, 20, 21, 22, 23, 29.
  9. Due Monday 10/26/20: Ch 2.2, Ex. 1, 2, 7, 8, 9, 11.
  10. Due Monday 11/2/20: Ch 2.2, Ex. 16, 17, 18, 21, 24, 29.
  11. Due Monday 11/9/20: Ch 2.3, Ex. 1; Ch 2.B, Ex. 1, 2, 3, 4, 8.
  12. Due Monday 11/16/20: Ch 2.B, Ex. 10; Ch 2.C, Ex. 4, 5.
  13. Due Monday 11/23/20: Ch 3.1, Ex. 3, 4, 5, 6, 11, 13.
  14. Due Friday 12/4/20: Ch 3.2, Ex. 4, 8, 12; Ch 3.3, Ex. 6, 7, 8, 24, 26.