ChrisLazda
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Registered User
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Jun 7 |
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A category with weak equivalences which is not a model category Take a look at this question mathoverflow.net/questions/23269/… |
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May 7 |
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What can be said about this morphism of sheaves Yes, this is how you show that categories of sheaves/$\mathcal{O}_X$-modules have enough injectives, see for example the first few sections of Chapter III of Hartshorne. |
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Apr 8 |
awarded | ● Commentator |
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Apr 8 |
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Hypercohomology of a complex via Cech cohomology I can't think of a reference, but I have a vague recollection that this is how you do it: since the Cech complex of a sheaf is functorial, if we have a complex of sheaves $\mathcal{F}^{\cdot}$ we can take the Cech complex of each term to get a double complex $C^{\cdot,\cdot}$. Now just take the associated simple complex, $\mathrm{Tot}(C^{\cdot,\cdot})$ - in suitably nice situations, this computes hypercohomology of $\mathcal{F}^{\cdot}$. |
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Mar 27 |
answered | Why is a proper, affine morphism finite? |
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Mar 26 |
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Overconvergent/infinitesimal site, base change and six operations added 336 characters in body; added 12 characters in body; deleted 6 characters in body |
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Mar 26 |
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Overconvergent/infinitesimal site, base change and six operations At least for F-isocrystals, 6 operations has now been worked out by Caro - he has a good theory of overholonomic F-D modules which are stable under all operations and contain the category of overconvergent F-isocrystals. On quasi-projective varieties he has proved stability of holonomicity (with F-strucure). I am specifically curious as to whether one might hope to make 6 operations work within le Stum's framework, because this base change business seems to suggest not (to me anyway). |
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Mar 26 |
awarded | ● Yearling |
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Mar 26 |
awarded | ● Yearling |
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Mar 26 |
asked | Overconvergent/infinitesimal site, base change and six operations |
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Mar 18 |
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differential forms on formal schemes At least for varieties over a field of char 0 that is. |
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Mar 18 |
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differential forms on formal schemes A good place to look might be Hartshorne's paper on de Rham cohomology of algebraic varieties. archive.numdam.org/ARCHIVE/PMIHES/… In particular, Section 1.7 defines the object you talk about, and much of the paper is devoted to the study of its cohomology. |
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Mar 7 |
answered | How to see the geometry and arithmetic of tannakian fundamental groups? |
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Mar 6 |
asked | Pullbacks of intermediate/middle extensions and Gabber’s purity theorem |
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Mar 6 |
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Model category structures on dga’s in a ringed topos Thanks for the detailed answer, but I'm not sure I'm convinced. The link in David's comment suggests that in char p, dga's just don't form a model category. I can't see where the argument goes wrong though.. |
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Mar 6 |
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Model category structures on dga’s in a ringed topos Okay, so it seems that the answer is quite an emphatic no. However, I like the idea of using simplicial dga's instead, thanks for suggesting it! |
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Mar 5 |
revised |
Essential geometric morphisms on the étale site. added 391 characters in body |
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Mar 5 |
answered | Essential geometric morphisms on the étale site. |
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Feb 24 |
awarded | ● Nice Question |
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Feb 8 |
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Reference for rigid analytic GAGA Great, thanks. It was Köpf's paper that eventually came up after digging through Conrad's papers. |
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Feb 8 |
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Reference for rigid analytic GAGA His notes on rigid geometry didn't seem to have a reference. Rooting around some of his papers has done the job though, thanks! |
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Feb 8 |
asked | Reference for rigid analytic GAGA |
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Jan 31 |
answered | regular singularities |
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Jan 25 |
asked | Model category structures on dga’s in a ringed topos |
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Dec 25 |
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Tannakian fundamental group for finitely linear representation of group The pro-algebraic hull is the inverse limit over all finite dimensional representations of G of the Zariski closure of the image of G in GL_n. It's maybe worth pointing out that pro-algebraic hulls can be real beasts. For example, if G=Z, the integers, and k=C, the complexes, then the C-points of pro-algebraic hull is isomorphic to the direct sum of the additive group C and the group of all endomorphisms of the multiplicative group C^*. |
