13,709 reputation
12985
bio website front.math.ucdavis.edu/…
location Cornell
age 44
visits member for 4 years, 10 months
seen 16 mins ago
Math professor at Cornell, PhD 1996

Aug
17
awarded  Nice Answer
Aug
13
comment A special Lie subalgebra
I presume $add(x)$ means $ad(x)$?
Aug
11
answered “Mathematics talk” for five year olds
Aug
11
comment A question on non-archimedian Fourier transform
I would ordinarily think of a map $\mathcal S\to \mathcal S^0$, but you're regarding $\mathcal S^0$ as a subspace of $\mathcal S$. Is this by taking functions on $M(n)$ supported inside $GL(n)$, or is it by using the inner product somehow?
Aug
11
awarded  Nice Answer
Aug
11
revised Quotients by the additive group $\mathbb G_a$
added 31 characters in body
Aug
10
comment Quotients by the additive group $\mathbb G_a$
Fixed. $\ \ \ \ \ \ \ \ $
Aug
10
revised Quotients by the additive group $\mathbb G_a$
edited body
Aug
10
comment The target of a finite morphism $f$ is a dense open in $S$, can you extend $f$ to have target $S$?
A little more concretely: consider the sheaf of functions on $X$ that are integral over the subring of functions pulled back from $S$. Does the global $Spec$ of this sheaf of subrings give a $Y$?
Aug
9
answered Quotients by the additive group $\mathbb G_a$
Aug
9
revised Quotients by the additive group $\mathbb G_a$
fixed ldots
Aug
6
comment When is $(q^k-1)/(q-1)$ a perfect square?
Finite projective space, not plane, I would say.
Jul
31
comment Isomorphic Dual and Conjugate Representations of a Lie Algebra
Check it once and for all for the Lie algebra $End(V)$ itself. I'm voting to close as not research-level.
Jul
29
comment Poisson ideals vs. ideals generated by Poisson central elements
Okay, so the group-action analogue is that a $G$-invariant subvariety may fail to be the intersection of a number of $G$-invariant hypersurfaces.
Jul
29
answered Horn's inequalities for n matrices
Jul
29
accepted Poisson ideals vs. ideals generated by Poisson central elements
Jul
29
asked Poisson ideals vs. ideals generated by Poisson central elements
Jul
27
comment Are shortest halving curves simple closed geodesics?
I think this calculus of variations perspective makes clear that the more natural question is about curves with a fixed area to one side, where the area on the other side may be different (and even infinite).
Jul
25
comment Why do Lie algebras pop up, from a categorical point of view?
The derivations of an algebra form a Lie algebra.
Jul
24
comment Theorems for nothing (and the proofs for free)
Finite division rings commute.