This meeting will cover Chapter 2 (Sheaves) up through 2.2.6. (plus examples 2.2.9 and 2.2.10). The definition of sheaf is absolutely essential for what follows later in this course.

Read over the examples in 2.1.

- What is the definition of a presheaf on a topological space X?
- Do you see how differentiable functions on R^n can be made into a presheaf?
- Exercise 2.2.A. Aren’t we all category lovers?
- Do the terms “section” and “restriction” here carry their usual meanings?
- Work through the construction of the stalk at p of a presheaf.
- On a discrete topological space, how are the stalks related to sections?
- On the topological space X={p,q} with just three open sets {},{p},{p,q}, what is the stalk at q of a skyscraper sheaf at p?
- Do you see how the stalk is the colimit of a filtered index category?
- What two additional axioms make a presheaf a sheaf?
- Exercise 2.2.D.
- What is the constant presheaf on a topological space (Example 2.2.10.).
- How does the constant sheaf differ from the constant presheaf?

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