bio  website  math.temple.edu/~rivin 

location  USA  
age  
visits  member for  4 years, 1 month 
seen  2 hours ago  
stats  profile views  13,353 
Professor of Mathematics at Temple University.
8h

comment 
Riemann Mapping Theorem
Precomposing with $z \rightarrow 1/z$ reduces it to the standard Riemann Mapping Theorem. 
1d

answered  Geodesic paths on a flat sphere 
1d

comment 
Mean of a vector
Chapter V should work. (you have to be a little careful, since your linear transformations are not invertible, but semigroups are fine). Note that picking the triples randomly will both slow you down (when you pick three equal coordinates) and prevent you from jamming, as in @Henry's example). 
1d

answered  Mean of a vector 
2d

comment 
How can I express the following integral as special function?
Why do you believe that such an expression is possible? It is not too hard to get an infinite sum of Bessel functions... 
Dec 21 
comment 
Can a positive measure subset of a free group be nowhere dense?
@HJRW Sorry, I am quite dense: how so? 
Dec 21 
comment 
Can a positive measure subset of a free group be nowhere dense?
@HRJW how is this dense in $\mathbb{Z}?$ It has natural density $0,$ so does not contain any arithmetic progression... 
Dec 21 
answered  Can a positive measure subset of a free group be nowhere dense? 
Dec 21 
answered  Is there any elementary proof of No wandering domain for polynomials 
Dec 21 
answered  Do geodesics in SL2R map to geodesics in the hyperbolic plane? 
Dec 19 
answered  How many ksubsets of the integers {1,…,n} sum to N? 
Dec 19 
answered  Nonperiodic points of homeomorphisms of a ball 
Dec 17 
comment 
Gaussian Elimination for Orthogonal groups
What exactly do you want to accomplish by this? 
Dec 17 
answered  Hypergeometric function 2F1 convexity proof: 
Dec 14 
answered  Dilatation of surface diffeomorphisms 
Dec 14 
comment 
Measuring the Randomness and Statistics of Convex Polygons
For example, one can generate random points on the circle... 
Dec 8 
answered  Why do Pell equations appear in Ramanujan's pi formulas? 
Dec 8 
comment 
What kind of complex surfaces are analogous to rotation surfaces?
Rotation surface = surface of revolution? 
Dec 7 
answered  Proving a random bipartite graph contains a perfect matching 
Dec 3 
answered  Generalization of Pascal's Theorem to Higher Dimensions 