25,856 reputation
166152
bio website rybu.org
location Victoria, BC
age 41
visits member for 5 years, 6 months
seen 13 hours ago
I'm a professor of mathematics at the University of Victoria, in BC Canada.

16h
reviewed Close Fun math puzzle
May
19
awarded  Nice Answer
May
19
reviewed Close Isometric imbedding of finite metric space into standards spaces
May
19
reviewed Close How can two random variables are continuous infers that their jointly random variable is continuous
May
18
reviewed Close relation between characters
May
18
reviewed Close Order of element in algebraic group
May
18
comment Intrinsic definition of arc length
There's the Cauchy-Crofton formula for the arc length of a curve. It does not use a parametrization. It also generalizes to formulas for surface areas, etc. en.wikipedia.org/wiki/Crofton_formula The Crofton formulas also have versions that work for parametrized curves (arc length) vs. just the image/trace of the curve.
May
13
reviewed Close Compactification of Separable metric space , What is its use?
May
13
reviewed Close Convergence of series made out of Markov Chain
May
12
reviewed Close Smallest sum of original column entries in 2d matrix
May
12
reviewed Close Integral kernels of self-adjoint operators
May
11
reviewed Close Length of quotients and relations between $\ell(\mathrm{coker}\varphi),\ell(R/\det\varphi)$
May
11
reviewed Close two tailed unequal variance t-test
May
11
reviewed Close Order statistics: does distribution of sum of two of them uniquely determine parent distribution?
May
11
reviewed Close Why is the evaluation map of sheaves injective
May
11
reviewed Close When does a function space allow for point evaluations?
May
11
reviewed Close Question about Eigenvalues of group elements
May
11
reviewed Close Time to stable phase for the classic Susceptible-Infected-Susceptible epidemic model
May
11
comment Is the space of immersions of $S^n$ into $\mathbb R^{n+1}$ simply connected?
@YCor: you are describing what is known as "regular isotopy". Isotopy is a 1-parameter family of diffeomorphisms of the target space.
May
8
comment Is the space of immersions of $S^n$ into $\mathbb R^{n+1}$ simply connected?
@YCor: this is smooth immersions up to 1-parameter families of immersions. Sometimes this is called "regular isotopy" to distinguish it from "isotopy". We're talking about the homotopy-type of the space of immersions. Immersions up to plain isotopy have an enormous amount of components, primarily indexed by the image (as a stratified space).