4,173 reputation
23965
bio website
location Minneapolis
age
visits member for 5 years, 2 months
seen 2 days ago
After doing nearly all the coursework for a Ph.D. in math, I then did all the coursework for a Ph.D. in statistics and completed that degree.

2d
comment Which classes of functions are “convolution ideals”?
I notice that functions having bounded support are not such an "ideal".
Jul
27
comment Is there a name for this quantity between two distributions?
You're using the word "sample" incorrectly. You should say $x_1,\ldots,x_n$ is a sample from $f$, not that $x_1,\ldots,x_n$ are samples from $f$. ${}\qquad{}$
Jul
17
revised From Planar Graphs To Tangent Circles
added 6 characters in body
Jul
17
comment Oriented volume and determinants: Circularity
I think I've seen some definition of a "frame" according to which that concept is more general that that of a basis. ${}\qquad{}$
Jul
17
revised Oriented volume and determinants: Circularity
edited body
Jul
17
comment Oriented volume and determinants: Circularity
@PaulReynolds : Could you explain what a frame is? Or perhaps a real frame? And then make your comments into an answer? ${}\qquad{}$
Jul
17
comment Which classes of functions are “convolution ideals”?
@PeterMichor : What do you mean by "fix the given function space under convolution"? Do you mean the space is closed under convolution? But how would a particular algebra "close" it under convolution if that's what is meant? ${}\qquad{}$
Jul
17
revised Which classes of functions are “convolution ideals”?
added 4 characters in body
Jul
17
revised How to compute this $\mathrm{Ext}^1$?
proper use of \cdots and \ldots
Jul
17
revised What are examples of good toy models in mathematics?
added 22 characters in body
Jul
17
revised Which classes of functions are “convolution ideals”?
added 5 characters in body
Jul
16
comment Which classes of functions are “convolution ideals”?
@YemonChoi : I had in mind $\mathbb R$ or $[0,\infty)$ or $\mathbb R^n$ or whichever generalizations might be interesting. ${}\qquad{}$
Jul
16
revised Which classes of functions are “convolution ideals”?
added 182 characters in body
Jul
16
comment Which classes of functions are “convolution ideals”?
The class of probability densities is closed under convolution, but is NOT an example of the sort above: If you convolve an arbitrary function with a probability density, you don't generally get a probability density. Nor do probability densities form an algebra.
Jul
16
comment Which classes of functions are “convolution ideals”?
@GerhardPaseman : But "closed under convolution" is not the same thing. I'm not talking about classes of functions for which if two functions belong to it, then so does their convolution. Rather this is about classes of functions for which if just one of the two belongs, then so does their convolution. Each of my examples is also an algebra, although I didn't mention that above. ${}\qquad{}$
Jul
16
revised Isotropic subvarieties of $ V(x_1^2+\dots+x_n^2-t_1^2-\dots-t_n^2) $
added 1 character in body
Jul
16
revised Isotropic subvarieties of $ V(x_1^2+\dots+x_n^2-t_1^2-\dots-t_n^2) $
added 15 characters in body
Jul
16
asked Which classes of functions are “convolution ideals”?
Jul
16
revised Why is the Gamma function shifted from the factorial by 1?
added 16 characters in body
Jul
13
comment When to postpone a proof?
When it's too long to fit in the margin.