1,762 reputation
512
bio website
location
age
visits member for 4 years, 2 months
seen yesterday

Sep
24
answered Every representation of a finite group is reducible?
Sep
24
comment Can a free group over a set be constructed this way (without equivalence classes of words)?
In the normal definition of the free group using words, the tedious part is associativity. Using this strategy for the proof, I feel like this complexity is pushed into showing that the "monoid quotient" by (x.i(x)=1) preserves the multiplication in the monoid (so that the quotient is still a monoid). Is there an easy way of proving this?
Aug
6
awarded  Yearling
Nov
16
comment Time in Mathematics
Homotopy theory is really all over the place, I probably couldn't give a better reference than Hatcher's Algebraic Topology. For Lie theory, I would suggest John Stillwell's Naive Lie Theory. It only requires linear algebra and calculus and focuses on examples.
Aug
6
awarded  Yearling
Apr
16
comment Nice examples of groups which are not obviously groups
The easy way to see that this is a group (and the reason you got downvoted I expect) is that this is easily seen to be a group of matrices because the action of PSL(2,C) matrices on the extended complex plane by möbius transformations is actually just the action of PSL(2,C) on CP^1 by linear transformations, and that is easily seen to be a group if you know the properties of matrix multiplication.
Oct
2
accepted $\mu$ on $\mathcal{A}$ is $\sigma$ finite if and only if $\mu$ on $R$ is $\sigma$ finite
Sep
29
answered $\mu$ on $\mathcal{A}$ is $\sigma$ finite if and only if $\mu$ on $R$ is $\sigma$ finite
Sep
23
comment $\mu$ on $\mathcal{A}$ is $\sigma$ finite if and only if $\mu$ on $R$ is $\sigma$ finite
It is a problem in Benedetto and Czaja "Integration and Modern Analysis". I think I found a solution to the problem now, should I post it as an answer here myself?
Sep
22
asked $\mu$ on $\mathcal{A}$ is $\sigma$ finite if and only if $\mu$ on $R$ is $\sigma$ finite
Aug
6
awarded  Yearling
Mar
28
answered How can one visualize topological quotients or develop intuition for handling them?
Mar
20
comment Applications of the p-adics
Measuring the circumference of a circle by knowing its diameter, perhaps?
Mar
20
answered Matchings Containing Given Edges
Mar
8
comment looking for an imbedding of the Torus in 3-dimensional euclidean space
Be careful with this. If you choose the parameters $R=r=1$, then your torus will not have a real hole in the middle (see the "horn torus" picture). Look on the wikipedia page, it says that $R$ is the distance between the center of the "hole" and the center of the "tube" around it, and $r$ is the radius of the tube. If $r \geq R$ then you won't get a real hole, better to choose values like $R=2$ and $r=1$. These radii do not need to be both $1$ since stretching the torus does not change its topology.
Mar
8
comment Iterate the points around the edge of a rectangle
How are you given the data of the "rectangle"? The coordinates of its four corners? A list of the lattice point it intersects? the coordinates of two opposite corners?
Mar
8
answered looking for an imbedding of the Torus in 3-dimensional euclidean space
Feb
6
answered what is Prime Gaps relationship with number 6?
Jan
26
answered Does any rotation matrix in 3-d space have only one non-zero eigenvector?
Jan
25
awarded  Benefactor