15

Answers

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7

Is the dual notion of a presheaf useful?

4

Checking whether the image of a smooth map is a manifold

4

Question about the fundamental group and homotopy equivalence

7

Can the n-string sphere braid group embed in to the (n+1)-string sphere braid group?

5

Pointed vs. unpointed homotopy colimits

6

What are normalized singular chains good for?

1

Functorial properties of blow-up

11

Are there homotopy equivalences that are not weak homotopy equivalences?

8

Obstruction theory for non-simple spaces

2

Is the derived category of abelian groups a subcategory of the stable homotopy category?

1

A version of the group ring using direct product rather than direct sum?

6

Example: a pair of nonisomorphic parallel morphisms with isomorphic cones

2

Do we have a pullback operation on simplicial chains?

2

Cohomology of Complements by an analytic subset?

3

Borel localization with Mayer-Vietoris sequence