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bio website people.brandeis.edu/~jbellaic
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Professor of Mathematics at Brandeis University


Jun
11
comment Can every commutative ring of characteristic $p\in\mathbb P$ be written as the form $R/(p)$ with $R$ being a ring of characteristic $0$?
But then your second question needs precisions. It seemed to me it has been answered by Qiaochu's comment. But if you think otherwise, it is that I haven't understood the question as you intended it. Do you ask for which $S$ there exists a universal $R$? Anyway, I think you should throughly edit your question, removing the first question which has a trivial answer (or leaving it but indicating it has a trivial answer) and emphasizing the second one, formulated more carefully...
Jun
11
comment Can every commutative ring of characteristic $p\in\mathbb P$ be written as the form $R/(p)$ with $R$ being a ring of characteristic $0$?
@Censi Li: Perhaps I have not said exactly what I meant: I meant a formulation of the question that makes it non-trivial. As it stands, it has the trivial answer $R=S \times \mathbb Z$ as proposed by LMB, and it is too easy a question for MO. If you can reformulate it in a way it has a non-trivial and useful answer, then I would be happy to vote to reopen it.
Jun
11
comment Can every commutative ring of characteristic $p\in\mathbb P$ be written as the form $R/(p)$ with $R$ being a ring of characteristic $0$?
I have given the final vote to close, until the question is made more precise.
May
26
awarded  Popular Question
May
24
comment On sentences true in all finite groups
@Christian: what about $w=x^2$? or $w=x^n$ for any $n \in \mathbb Z$? or $w=y x y^{-1}$? All those words are $1$ for $x=1$ whatever the value of $y$.
May
14
accepted Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics)
May
14
revised Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics)
added 608 characters in body
May
14
comment Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics)
Thanks a lot. That doesn't leave much hope for a positive answer in the case of an intersection of quadrics, though I would love to see a counter-example. Very good blog post, by the way...
May
14
revised Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics)
added 1 character in body
May
14
revised Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics)
added 453 characters in body; edited tags
May
14
asked Upper bound on Betti numbers of an intersection of hypersurfaces (or quadrics)
Apr
24
awarded  Nice Question
Mar
24
comment Did Grothendieck write about modular forms?
Good quote! This is the way Grothendieck could have become interested in the Langlands program : not by the modular forms, too special, too peculiar, to computational for his taste, but by the great vision of Langlands using Motives, Tannakian Categories. How wonderful would have it been if Grothendieck had learnt this theory and worked on it.
Mar
22
awarded  Good Answer
Feb
25
awarded  Good Question
Jan
6
answered Examples of component crossing between families of modular forms
Jan
5
comment In “splendid isolation”
Very surprising and interesting story! It means that great physicists like Bohr and Heisenberg were not completely familiar with multiplication of matrices. Or do I understand wrongly this passage ? In general relativity for example, multiplication of matrices (and tensors) is everywhere...
Jan
1
awarded  Nice Question
Dec
8
comment The resolution of which conjecture/problem would advance Mathematics the most?
I am not an expert but there are counter-examples to the conjecture "with coefficients" since about 20 years (due to V. Lafforgue and others). Is the conjecture without coefficients almost as useful than the conjecture in general ?
Nov
25
comment short character sums averaged on the character
Thanks for this answer, Lucia.