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bio website perso.univ-rennes1.fr/…
location Rennes
age 37
visits member for 3 years, 11 months
seen 39 mins ago

1d
comment Push-out and non-reduced schemes
I still don't really have ideas (although I am rather pessimistic), but I now wonder: why do you require the diagram to be cartesian? Usually cocartesian diagrams are not cartesian, and there is no reason to require that a pushout diagram be.
1d
revised Idempotent fractional ideals of a Noetherian domain
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2d
revised Idempotent fractional ideals of a Noetherian domain
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2d
comment Idempotent fractional ideals of a Noetherian domain
Great, thanks! I should have tried such an example...
2d
accepted Idempotent fractional ideals of a Noetherian domain
2d
comment Idempotent fractional ideals of a Noetherian domain
Yes I tried, but there are several triples $(A,I,M)$ (ring, ideal, f.g. module) that one can try and none gave the result. For instance taking $A=R+J$ and $I=M=J$ I could prove that $R\subset J$ but then?...
2d
revised Idempotent fractional ideals of a Noetherian domain
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2d
asked Idempotent fractional ideals of a Noetherian domain
Apr
16
answered “Resume de cours” by J. Tits
Apr
4
comment Subcategories of abelian categories generated by finitely many objects
Why should one want the abelian closure to be closed under taking extensions? If this condition is not required, it seems to me that one gets a sub-abelian category with exact inclusion (which is fine enough) but maybe not closed under isomorphisms.
Mar
28
comment A quotient stack question
@ACL: in fact normalization commutes with smooth localization, hence is well-defined for Artin stacks. This is proved in Laumon and Moret-Bailly's book.
Mar
21
comment Is there any rational curve on an Abelian variety?
@Felipe Voloch: but then you end up using the fact that you wanted to prove (that a map from $P^1$ to an ab. var. is constant).
Jan
20
revised Has anyone found an error in an early version of Neukirch?
edited body
Jan
20
awarded  Necromancer
Jan
19
revised Has anyone found an error in an early version of Neukirch?
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Jan
19
revised Has anyone found an error in an early version of Neukirch?
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Jan
19
revised Has anyone found an error in an early version of Neukirch?
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Jan
18
answered Has anyone found an error in an early version of Neukirch?
Jan
10
awarded  Popular Question
Jan
3
awarded  Nice Question