4,086 reputation
2248
bio website quora.com/Alon-Amit
location Los Altos, CA
age 46
visits member for 5 years, 10 months
seen Jul 13 at 7:47

Dabbler in things.


Apr
21
answered Connectedness of random distance graph on integers
Apr
21
comment Enumeration of Regular Graphs
I don't think there's any closed form formula, but you can compare your results with the data in OEIS, such as here: oeis.org/A005638 (for 3-regular graphs) or here: oeis.org/A051031. This is indexed by the number of vertices, not edges, but of course for fixed k this is the same up to a factor of k/2.
Apr
5
comment What's the name of this 2D cellular automaton?
Sounds familiar but I can't quite place it off the top of my head. Places to look would be the chapters on cellular automata in Gale's "Tracking the automatic ant", and of course Gardner's books and perhaps Hofstadter's collections from Sci Am.
Mar
22
revised Open source mathematical software
minor typo
Mar
22
answered Open source mathematical software
Mar
19
revised What are the worst notations, in your opinion ?
added 24 characters in body
Mar
19
comment What are the worst notations, in your opinion ?
@Qiaochu: I'm really only talking about the interior case. It's then that the \osum is the same subspace as the sum but with the implied additional condition on the subspaces.
Mar
19
comment how slow can the dimension of a product set grow?
So the circle S^1 has dimension 2 in your sense? If so, I don't know if this has a name but I certainly wouldn't recommend "dimension".
Mar
19
comment What are the worst notations, in your opinion ?
@Francois: Sheesh, of course. Sorry. Fixed.
Mar
19
revised What are the worst notations, in your opinion ?
deleted 4 characters in body; added 11 characters in body
Mar
18
answered What are the worst notations, in your opinion ?
Mar
17
comment Fundamental groups of noncompact surfaces
If I had been faster I would have proposed the same reference so you wouldn't have had to advertise your own book. I'm a fan :-)
Mar
16
comment Properties of Graphs with an eigenvalue of -1 (adjacency matrix)?
If G->B is a covering map (in the topological sense), then G inherits all the eigenvalues of B (just choose an eigenfunction that is uniform on the fibers). So, for instance, any graph which covers K_n for any n has -1 as an eigenvalue. The cycle of length 3k covers the triangle, which is another way to explain Kevin's example.
Mar
16
awarded  Nice Answer
Mar
16
awarded  Popular Question
Mar
14
awarded  Enlightened
Mar
14
awarded  Nice Answer
Mar
12
comment Books you would like to see translated into English.
That's +10 from me, too.
Mar
10
answered A historical question: Hurwitz, Luroth, Clebsch, and the connectedness of M_g
Mar
9
revised Why are the sporadic simple groups HUGE?
added 2 characters in body