3,332 reputation
1938
bio website mathematik.uni-mainz.de/…
location Mainz
age 27
visits member for 5 years, 6 months
seen Aug 19 at 16:07

Post-doc at Johannes-Gutenberg Universität Mainz. Interested in many things, but especially arithmetic geometry.


Aug
17
comment Isotrivial families with non-zero Kodaira spencer map
@JasonStarr How can one get rid of the assumption on the characteristic of $k$? It seems to me that if, for instance, the morphism $\pi$ were finite type, we don't need $k$ to be of characteristic zero. Does that seem right to you?
Aug
17
comment Isotrivial families with non-zero Kodaira spencer map
@JasonStarr You wrote "Since k is algebraically closed, there exists a dense open subscheme of I that is k-scheme." Did you mean to write "Since $k$ is algebraically closed and of characteristic zero, there exists a smooth dense open subscheme of $I$ over $k$"?
Aug
7
comment Is a morphism whose all fibers are $\mathbf{P}^n$ a projective bundle?
@grghxy That is indeed very beautiful. Thank you.
Aug
7
revised Is a morphism whose all fibers are $\mathbf{P}^n$ a projective bundle?
deleted 24 characters in body
Aug
7
comment Is a morphism whose all fibers are $\mathbf{P}^n$ a projective bundle?
@grghxy Thank you for your comment as well. I added this to the "answer". I really feel like the OP might find this useful, so I'm not deleting it unless it turns out to be completely wrong. :)
Aug
7
revised Is a morphism whose all fibers are $\mathbf{P}^n$ a projective bundle?
my answer didn't answer the question. I left my comments for the OP, as they might be useful.
Aug
7
comment Is a morphism whose all fibers are $\mathbf{P}^n$ a projective bundle?
@JasonStarr Thank you for your comment. I read the question too quickly. I will edit the "answer" accordingly. Why does the Isom-scheme argument only apply if the morphism is projective?
Aug
7
answered Is a morphism whose all fibers are $\mathbf{P}^n$ a projective bundle?
Jul
21
comment Automorphisms of del Pezzo surfaces
I think the discussion on the bottom of page 36 of jlms.oxfordjournals.org/content/s2-32/1/31.full.pdf might be useful to you.
Jun
23
comment Excellent rings
Note that Example 13 in Koll\'ar's paper also gives an example with $A$ regular, but only in characteristic two.
Jun
16
revised Are all these K3 surfaces supersingular?
Added tags because this question didn't get any attention (probably because it wasn't tagged well)
Jun
9
revised Families of Fano varieties over non-hyperbolic curves
typos corrected
Jun
9
revised Families of Fano varieties over non-hyperbolic curves
deleted 430 characters in body
May
27
answered Obstruction to get a galois invariant cycle
May
18
reviewed Approve What is prime power of this equation of p?
May
15
revised Abelian varieties with good reduction everywhere over function fields
Added a sentence to explain second paragraph of answer
May
15
reviewed Approve Kernel of flux homomorphism (Calabi invariant) for volume-preserving maps on a compact manifold
May
12
reviewed Approve Algebraic proof of Five-Color Theorem using chromatic polynomials by Birkhoff and Lewis in 1946
May
12
reviewed Approve Question about a divisor and its image
May
6
comment Do line bundles descend to coarse moduli spaces of Artin stacks with finite inertia?
Dear @ZsoltPatakfalvi, you're right. That's not a good test case.