9
votes
2answers
335 views
Anything special (historical?) about surface $x\cdot y\cdot z\ +\ x+y+z=0$?
QUESTION
I wanted to introduce and develop the complex logarithm from scratch. As the result I've arrived a couple of months ago at the following identity after which the road to …
1
vote
2answers
146 views
A machine learning application question
I am familiar with basic probabilities, random processes but not so much of machine learning methods. This is the problem I am trying to solve.
I want to predict the nature of use …
1
vote
1answer
19 views
Closure of one relation w.r.t other
I have two relations R and R' satisfying following property -
R(a,b) & R'(a,a') & R(a',b') => R(a,b')
Pictorially, it looks like this -
a --(R)-> b
| \
(R') \ (* n …
14
votes
2answers
2k views
Nonseparable example in dimension theory?
Could you give me an example of a complete metric space with covering dimension $> n$ all of which closed separable subsets have covering dimension $\le n$?
The question close …
0
votes
1answer
197 views
Number of blocks in a t-(v,k,l) design with empty intersection with a given set U
Question
Given a $t-(v,k,\lambda)$ design $(X,\mathcal{B})$ and a set $U\subset X$ with $|U|=u\leq t$, what is the number of blocks $B\in\mathcal{B}$ such that $B\cap U=\emptyset$? …
0
votes
0answers
5 views
How can this fail if my pairing is nondegenerate?
I have two infinite-dimensional (Frechet) linear spaces $X$ and $Y$ over $\mathbb R$, and a nondegenerate pairing $\langle\cdot,\cdot\rangle:X\times Y\to \mathbb R$. Neither $X$ no …
2
votes
2answers
107 views
Where is the belly button of the Universe?
It's fine and nice and wonderful when a part of learning mathematics is chaotic, ad hoc, spontaneous, social, ...
However it would be perhaps of fundamental value to know a very c …
0
votes
0answers
12 views
Existence of particular embeddings in euclidean spaces for non compact manifolds
Let $M$ be a $n$-dimensional smooth connected not compact manifold s.t. groups (singular cohomology)
$H^{k}(M,\mathbb{Z})$ are finitely generated for $k\geq 0$. Can we find a suff …
0
votes
1answer
43 views
Inverse (in)degree of a digraph
Hi All,
here is my question. I'm given a directed graph $(V,E)$ with $|V| = n$ vertices and in-degrees $d_1$, $d_2$ ... $d_n$ (so that $\sum_i d_i = |E|$). Can we upper bound the …
0
votes
1answer
322 views
biharmonic morphisms
My question is related to the Riemann Mapping Theorem. A function $f$ is biharmonic if $\Delta^2f=0$.
Let $D$ be a simply connected domain in $\mathbb{R}^2$ and denote by $B$ the …
0
votes
0answers
23 views
What is the inverse of this kind of integral transform?
Let $$\hat{f}(\lambda):= \int_0^{+\infty}K(x,\lambda)\ f(x)\ dx, \text{where } K(x,\lambda)=\sqrt{\frac{2}{\pi}}\frac{\lambda \cos(\lambda x)+h\sin(\lambda x)}{\lambda^2+h^2}$$
be …
0
votes
0answers
88 views
What’s wrong with this arithmetic model for the change in the perception of “number” of quantum states? [closed]
Maybe one of the strange things about quantum mechanics comes from the mental dificulty of reconciling the fact that a system in a superposition of several states, when measured or …
1
vote
0answers
13 views
How many trees can be constructed from k vertices using an LCA operator?
Consider the class of rooted trees and suppose I have at my disposal a lowest common ancestor (LCA) operator given by
$$
\textrm{lca}(u,v) = \text{the lowest common ancestor of $u$ …
4
votes
3answers
133 views
The “right” $C^*$ algebraic proof of Bott Periodicity
In learning about the K-theory of $C^*$-algebras, I have encountered the following 3 proofs of Bott periodicity:
$\bullet$ An argument based on Moyal quantization found in "Elemen …
10
votes
1answer
269 views
Covariance of INID order statistics
In the IID case, it is known that all order statistics are positively correlated.* Thus, we know that $$\text{Cov}(X_{(i)},X_{(j)}) \geq 0.$$ Is this known in the INID (independe …

