3,903 reputation
1943
bio website quora.com/Alon-Amit
location Los Altos, CA
age 45
visits member for 4 years, 10 months
seen Jun 21 at 7:14

Dabbler in things.


Sep
29
awarded  Yearling
Jul
27
revised Point sets in Euclidean space with a small number of distinct distances
Fixed exponent of n to 77/141.
Jul
24
awarded  Nice Answer
Jul
7
awarded  Nice Answer
Sep
30
awarded  Yearling
Sep
19
revised Number of finite simple groups of given order is at most 2 - is a classification-free proof possible?
Added a few LaTeX tags.
Sep
19
comment out-trees and least upper boundness
I'm still very confused. Yes, lattices contain semicycles, that's just the point - you were asking if every LUB graph is a (kind of) tree, and it isn't. You now changed the question to ask if every connected digraph without semicycles (which further satisfies LUB) must be a (kind of) tree. Well, it is, by definition, right? The underlying undirected graph certainly is a tree (connected and cycle free). This is just an out-tree except that we haven't chosen a specific root.
Sep
16
comment Finite simple groups and conjugacy classes with 2p elements
Is it known that this can't occur with the alternating groups? Empirically it looks like the sizes of the conjugacy classes of $A_n$ all have at least 3 prime factors once $n>8$.
Sep
16
comment Spanning trees in 3 regular graphs.
What do "clip" and "half edges" mean?
Sep
15
answered out-trees and least upper boundness
Sep
11
comment Second eigenvalue of suspension of a graph
Shouldn't you be looking at the Laplacian, rather than the adjacency matrix? For non-regular graphs I'm not sure if the second largest eigenvalue is the thing that controls mixing. Also, the operation you're interested in seems more like taking the cone over $G$, rather than a suspension.
Sep
2
revised Do good math jokes exist?
Fixed broken YouTube link.
Aug
26
revised Theorems for nothing (and the proofs for free)
typo correction.
Aug
5
comment What are some proofs of Godel's Theorem which are *essentially different* from the original proof?
An awesome summary!
Jul
28
revised Maximal ideals in the ring of continuous real-valued functions on R
LaTeXification.
Jul
28
comment What should be learned in an introductory analytic number theory course?
I'm curious: what is "Pollack's new book"?
Jun
18
comment Gently falling functions
Sorry if that's a silly question but in example 1), a particle starting at (0,1) won't go anywhere unless you give it some initial horizontal velocity. Are you suggesting that the separation point tends to the indicated point as that velocity tends to 0?
Jun
17
comment Proof that any NP problem can be reduced (in P time) to any problem in NPC?
I don't understand your modified question. Of course every problem in NP can be reduced some subset of NP problems - it can be "reduced" to itself, and often to lots of other problems polynomially-equivalent to it. Why does that imply that NPC is empty?
Jun
11
comment Is there any sequence $a_n$ of nonnegative numbers for which $\sum_{n \geq 1}a_n^2 <\infty$ and $\sum_{n \geq 1}\left(\sum_{k \geq 1}\frac{a_{kn}}{k}\right)^2=\infty$?
In line 3, did you mean "the sequence whose $n$-th term is..."?
Jun
3
comment Examples of theorems misapplied to non-mathematical contexts
If he does, it's a slam dunk.