30,288 reputation
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bio website math.tsukuba.ac.jp/~carnahan
location 筑波市, Japan
age
visits member for 5 years, 5 months
seen Mar 22 at 4:58
I think this is a neat project.

Mar
26
awarded  Good Answer
Mar
21
comment $\mathcal{M}_{g,n}$ a scheme for $n \gg 0$?
Bjorn's comment under JSE's answer addresses the representability question. The absence of automorphisms automatically yields an algebraic space, but the coarse moduli space is known to be a quasi-projective variety, so you get a scheme.
Mar
21
comment $\mathcal{M}_{g,n}$ a scheme for $n \gg 0$?
This is covered in mathoverflow.net/questions/11253/… . See in particular JSE's answer.
Mar
18
awarded  Nice Answer
Mar
6
comment Maryam Mirzakhani's works
In general, if you want to know about a Fields Medalist's (pre-medal) work, the Laudationes is a good place to start, and is available at the IMU website.
Mar
6
comment When an elliptic curve is a quotient of $\mathbb{G}_a$?
The exponential function doesn't converge on the whole Lie algebra. Even after restriction, I think surjectivity would require base change to some period ring.
Mar
5
comment When an elliptic curve is a quotient of $\mathbb{G}_a$?
There is a $\mathbb{G}_m$-uniformization of $p$-adic analytic elliptic curves with bad reduction. However, the exponential function isn't $p$-adically entire, so lifting to an additive uniformization seems difficult.
Mar
3
comment Definition of internal field objects
This might be the discussion you remember: mathoverflow.net/questions/3003/…
Mar
2
reviewed Close Embedding rational simple algebras in the real quaternions
Feb
27
reviewed Close Practical Way to Detect a Markov Chain is Regular Given the Transition Matrix
Feb
25
comment Automorphisms of a quotient variety
For your example, don't you need your automorphism of $\mathbb{A}^n$ to commute with the action of $k^\ast$?
Feb
20
comment Artin approximation of a diagram
Could you make the statement of your question more precise?
Feb
20
comment Axioms for sheaf cohomology
You should ask Tyler. It would be unfair for me to delete his contribution without his consent.
Feb
19
awarded  Nice Answer
Feb
19
comment Concise mathematical definition of the fusion product on the Verlinde ring?
@DavidRoberts Fusion rules are defined as dimensions of certain vector spaces, so any procedure that produces that number gives you a definition of fusion rule. Could you say a bit more about what sort of answer you are seeking?
Feb
19
answered Concise mathematical definition of the fusion product on the Verlinde ring?
Feb
16
reviewed Close Is there a nontrivial maximally recursive function?
Feb
15
reviewed Close “Parallel translate” of a geodesic in the following sense
Feb
15
comment Optimal shape for stabbing balls in $\mathbb{R}^3$
As Douglas Zare suggests, a tangent line has infinite expected hit/length ratio.
Feb
12
comment Constant group scheme and torsors
You should make $X$ into a pointed connected scheme to define $\pi_1(X)$, and your definition of torsor is missing the condition that $Y$ admits a local section. You have defined the notion of pseudo-torsor, and the empty scheme is a standard example of a pseudo-torsor.