bio | website | iazd.uni-hannover.de/… |
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location | Hanover, Germany | |
age | 30 | |
visits | member for | 5 years, 5 months |
seen | Aug 26 at 21:45 | |
stats | profile views | 2,571 |
I am a postdoc at the Leibniz UniversitÃ¤t Hannover. I specialise in arithmetic geometry, algebraic number theory and analytic number theory.
Aug
26 |
awarded | Popular Question |
Jul
25 |
asked | Finite-index subgroups of the ideles |
Jun
26 |
comment |
References for modular curves over finite fields
I'm voting to close this question as off-topic because this was answered on math.stackexchange. |
Jun
25 |
accepted | Specialisation of rigid varieties |
Jun
25 |
comment |
Specialisation of rigid varieties
Ok. If you know of any counter-examples in the Fano case, I would be most interested. |
Jun
25 |
comment |
Specialisation of rigid varieties
Is the Mukai-Umemura threefold really rigid? I thought that prime Fano threefolds of genus 12 had positive dimensional moduli. |
Jun
25 |
comment |
Specialisation of rigid varieties
Hi Jason. Thanks for the answer! Your examples seem to suggest that things are a lot better behaved in the Fano case. Do you know of any counter-examples to my question if I moreover assume that the special fibre and generic fibre are both Fano? |
Jun
25 |
asked | Specialisation of rigid varieties |
Jun
20 |
answered | meaning of $k$-rational for closed subschemes |
Jun
17 |
comment |
Number of solutions in a sum of squares Diophantine equation
I'm voting to close this question as off-topic because it has been answered. |
Jun
15 |
accepted | Non-algebraic K3 surfaces in characteristic $p$ |
Jun
15 |
comment |
Non-algebraic K3 surfaces in characteristic $p$
Quite possibly; does every non-algebraic K3 surface over $\mathbb{C}$ arise this way? |
Jun
15 |
asked | Non-algebraic K3 surfaces in characteristic $p$ |
Jun
8 |
accepted | Picard groups of Fano varieties in positive characteristic |
Jun
4 |
comment |
Picard groups of Fano varieties in positive characteristic
@Jason: I don't quite follow, what is the problem with small $\ell$? Is the issue with possible $\ell^\infty$-torsion in the Brauer group? Won't this problem "go away" as we are taking a projective limit over all $\mathrm{Br}[\ell^n]$? |
Jun
3 |
comment |
Picard groups of Fano varieties in positive characteristic
Thanks for the answer Jason. I will have a think about the argument you give. Do you know a precise reference where finiteness of the Brauer group of rationally connected varieties is proved? |
Jun
3 |
asked | Picard groups of Fano varieties in positive characteristic |
Jun
1 |
comment |
Isotropic ternary forms
Use stereographic projection. |
May
31 |
comment |
Are there infinitely many N^3 (especially for prime N) that cannot be expressed as a sum of three positive cubes?
Also, as you no doubt know, determining which integers are a sum of three (possibly negative) cubes is a very difficult open problem (see e.g. mathoverflow.net/questions/138886/…). One would think that your problem were easier as you are working with a cube, but restricting to positive cubes seems to complicate things. |
May
31 |
comment |
Are there infinitely many N^3 (especially for prime N) that cannot be expressed as a sum of three positive cubes?
This problem seems quite difficult. The issue, of course, is that there are no local obstructions in this case: there are always solutions in all $\mathbb{Z}_p$ and $\mathbb{R}$. So you would need to try to use a finer obstruction, e.g. a Brauer-Manin obstruction. |