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Announcements:

  • Our textbook is Algebraic Topology by Allen Hatcher. This is freely downloadable from Hatcher's web page.
  • Here are some suggestions for other books to look at.
    • J. R. Munkres, Elements of Algebraic Topology. Covers homology and cohomology very thoroughly.
    • E. H. Spanier, Algebraic Topology. One of the standard references in the field, but many people find it hard to read.
    • J. P. May, A Concise Course in Algebraic Topology. The topics and presentation are interesting, but at a fairly high level.
    • G. E. Bredon, Topology and Geometry. Nice book, has more on manifolds and less on homotopy theory, compared to Hatcher's book.

Reading

  • Section 2.1. See also my definition of Δ-complex (PDF).
  • Section 2.2
  • Section 2.3
  • The rest of Chapter 2: read whatever catches your interest

Homework:

  • Due Wednesday, October 4:
    1. Prove that the geometric realization of an abstract Δ-complex is the same as what Hatcher calls a Δ-complex.
    2. Check that ∂n−1n = 0 in my definition of the chain complex for an abstract Δ-complex.
    3. Section 2.1 of Hatcher (p. 131): 1, 4, 5, 8, 9, 11
  • Due Wednesday, October 11:
    1. Section 2.1 of Hatcher (p. 131): 16, 17, 18, 19, 20
  • Due Wednesday, October 18:
    1. Section 2.1 of Hatcher (p. 131): 19, 23, 26, 29
    2. For the 5-lemma (p. 129), what are the necessary hypotheses?
  • Due Wednesday, October 25:
    1. Read Hatcher's discussion of degree (pp. 134-137)
    2. Section 2.2 of Hatcher (p. 155): 1, 2, 3, 4
  • Due Wednesday, November 8:
    1. Section 2.2 (p. 155): choose two of 9(a), 9(b), 9(c), 9(d), 10, 12, 13
    2. Section 2.2 (p. 155): choose two of 17, 20, 26, 32, 33 (note that the Mayer-Vietoris sequence works in reduced homology but only as long as the intersection is nonempty), 38 (as mentioned in class)
  • Due Wednesday, November 22:
    1. Section 3.1 (p. 204): 2, 3, 4, 7

An equilateral triangle, barycentrically subdivided:

  • 2 times: (click on the image to see a larger picture, with size 78kb)
  • 3 times: (147KB)
  • 4 times: (315KB)
  • 5 times: (459KB)
  • 6 times: (1.6MB)
  • A crude animation (500KB)