All Questions
29
questions
4
votes
1
answer
190
views
Some questions on derived pull-back and push-forward functors of proper birational morphism of Noetherian quasi-separated schemes
Let $f: X \to Y$ be a proper birational morphism of Noetherian quasi-separated schemes. We have the derived pull-back $Lf^*: D(QCoh(Y))\to D(QCoh(X))$ (https://stacks.math.columbia.edu/tag/06YI) and ...
- 351
4
votes
0
answers
289
views
Are $\mathcal{O}_X$-modules "more actual" then quasicoherent sheaves in some sense?
In the Stacks project and in a book of Brian Conrad the "main" derived category of a scheme is the one of $\mathcal{O}_X$-modules. I would like to understand whether $D(\mathcal{O}_X)$ is ...
- 16.7k
9
votes
1
answer
903
views
Is the functor from the unbounded derived category of coherent sheaves into the derived category of quasi-coherent sheaves fully faithful?
Let $X$ be a Noetherian scheme. Is the obvious functor $D(\operatorname{Coh}(X))\to D(\operatorname{QCoh}(X))$ fully faithful?
If this is true then $D(\operatorname{Coh}(X))$ is equivalent to the full ...
- 16.7k
2
votes
1
answer
246
views
Semi-orthogonal decompositions over singular schemes
Where can I find any more or less explicit semi-orthogonal decompositions of derived categories of perfect complexes or of bounded derived categories for singular schemes that are proper over a ring R?...
- 16.7k
4
votes
1
answer
438
views
Perverse sheaves on the complex affine line
Show that a perverse sheaf on $\mathbb{A}^1(\mathbb{C})$ (the complex plane with the analytic topology) is a bounded complex $A$ of sheaves of $\mathbb{Q}$-vector spaces with constructible cohomology ...
- 1,479
2
votes
0
answers
269
views
Global Torelli and local Torelli for Fano threefolds (need reference)
It is known that in general Globally Torelli does not imply the local Torelli theorem, see
Is the Torelli map an immersion?
Globally Torelli means that the period map $\mathcal{P}$ is injective and
...
- 1,962
4
votes
0
answers
162
views
External tensor product Calabi-Yau DG categories
Let $\mathcal{C}$ be a smooth proper DG-category such that the shift $[p]$ is a Serre functor for $D^{perf}(\mathcal{C})$ (we say that $D^{perf}(\mathcal{C})$ is $p$-Calabi-Yau). I am looking for a ...
- 7,250
1
vote
0
answers
157
views
Correct reference for a proposition in a paper of Kapranov-Vasserot
In the paper "Kleinian singularities, derived categories and Hall algebras" Math. Ann. 316 (2000) of Kapranov-Vasserot, the authors write in page 569 that the complex $\mathcal{L}'$ (defined in p.568) ...
- 55
1
vote
2
answers
281
views
Faithfully flat modules over a group algebra
Suppose we have the following data:
1) A group ring $\mathbb{Z}[G]$, where $G$ is a torsion free group.
2) $M_{\bullet}$ a bounded (above and below) chain complex of $\mathbb{Z}[G]$-modules such ...
- 69
11
votes
1
answer
522
views
Non-Gorenstein Curves
I am interested in (as explicit as possible) descriptions of non-Gorenstein integral projective curves. Most of the literature on singular curves appears to be focused around the Gorenstein case, with ...
- 421
5
votes
2
answers
926
views
Does birational imply D-equivalent?
It is well-known that there are Calabi-Yau's who are not birational but are derived equivalent. However I am interested in seeing D-equivalence as a weakening of birationality.
Q. If $X$ and $Y$ ...
9
votes
0
answers
329
views
Is the perfectness of Fourier-Mukai kernels proved by Toen?
In Toen's paper The homotopy theory of dg-algebras and derived Morita theory, Theorem 8.15, he essentially proved the following result.
Let $X$ and $Y$ be two smooth and proper schemes over $k$. ...
- 8,767
2
votes
0
answers
213
views
Quantities associated to deformed sheaves
I am trying to figure out what happens to "quantities" associated to a sheaf when one deforms it. I am actually interested in deforming a bounded complex of coherent sheaves but I want to make the ...
- 155
3
votes
1
answer
558
views
Equivariant Derived Category
Can someone give me a reference for the following or an idea on why it is true? (This is taken from remark 1.5 on page 5 of http://arxiv.org/abs/0810.0794.)
Suppose we have an algebraic group $G$ ...
- 335
2
votes
1
answer
339
views
Is $K^0(X)\to K_0(X)$ monomorphic for a noetherian scheme $X$?
This question is related to the MO questions What is the difference between Grothendieck groups K_0(X) vs K^0(X) on schemes? and Does a fully faithful functor between triangulated categories induce ...
- 8,767