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19 votes
6 answers
2k views

Is the dual notion of a presheaf useful?

It seems that there is a common theme in mathematics where, if we want to find out about a category C, then we look at $\hat{C}$ (the category of contravariant functors from $C$ to $Set$). There are ...
Dylan Wilson's user avatar
  • 13.5k
18 votes
4 answers
6k views

Derived categories of coherent sheaves: suggested references?

I am interested in learning about the derived categories of coherent sheaves, the work of Bondal/Orlov and T. Bridgeland. Can someone suggest a reference for this, very introductory one with least ...
J Verma's user avatar
  • 3,218
10 votes
3 answers
2k views

Where can I find a proof of the de Rham-Weil theorem?

Where can I find a proof of the de Rham-Weil theorem? Does anyone know?
Louis A's user avatar
  • 360
8 votes
3 answers
643 views

Is there a name for a "rigid" sheaf?

Is there a name for the property of a sheaf $\mathcal F$ such that the restriction maps $\mathcal F(V) \to \mathcal F(U)$ are injective when $V$ is connected and $U$ is nonempty? In other words, this ...
Bruno Joyal's user avatar
  • 3,910
5 votes
1 answer
2k views

Generalized Beilinson spectral sequences

Assume we are workling on $\mathbb{P}^n$ for some $n\geq 1$ and we have a coherent sheaf $F$ on it. Then there are two (well known?) spectral sequences $E_r^{p,q}$ with $E_1$-term: $E_1^{p,q}=H^q(\...
TonyS's user avatar
  • 1,391