1
vote
1answer
135 views
Bounding Roots of a Polynomial by Coefficients
I'm using Samuelson's result and a chapter from Marden's monograph "The Geometry of Polynomials". These are sophisticated results. Are these independent from the Jury-Cohn test to …
1
vote
0answers
13 views
3-edge-coloring of 3-regular multigraphs
Given that a 3-regular multigraph is 3-edge-colorable, is there an expression for how many 3-edge-colorings exist?
(For example, if a 2-regular multigraph is 2-edge-colorable, the …
9
votes
1answer
345 views
A natural refinement of the $A_n$ arrangement is to consider all $2^n-1$ hyperplanes given by the sums of the coordinate functions. Have you seen this arrangement? Is it completely intractable?
The short version
Here is an extremely natural hyperplane arrangement in $\mathbb{R}^n$, which I will call $R_n$ for resonance arrangement.
Let $x_i$ be the standard coordinates …
0
votes
0answers
4 views
How do I calculate the “Area under the curve” AUC given TPR and FPR values?
Hi,
I am trying to rank my neural network, which is trained for binary classification. That is, given a set of input signals, it outputs either a 1 or a 0.
I have a training set, …
3
votes
1answer
30 views
How did Hankel determinants get the name Hankel-Hadamard?
My question concerns the name for determinants of Hankel-matrices $H = (s_{i+j})_{i,j = 0}^n$.
In the classical textbook of Shohat and Tamarkin (1943) "The Problem of Moments", th …
3
votes
0answers
27 views
Taylor Series and Fourier Series
Taylor series expansion of function, f, is a vector in the vector space with basis: {(x-a)^0, (x-a)^1, (x-a)^3, ..., (x-a)^n, ...}. This vector space has a countably infinite dimen …
0
votes
0answers
8 views
Understanding the rationale behind “batch means” estimation
Hello all,
I am implementing an MCMC algorithm for my work, and I've come upon something in the literature which I just can't understand.
Specifically, I am attempting to estima …
2
votes
1answer
169 views
Where did Sophus Lie write the group commutator for two one parameter groups.
If $X,Y$ are vector fields and $\def\Fl{\operatorname{Fl}}\Fl^X_t$ and $\Fl^Y_t$ their local flows, let $[\Fl^X_t,\Fl^Y_t]:= \Fl^Y_{-t}\Fl^X_{-t}\Fl^Y_t\Fl^X_t$ denote the group co …
3
votes
1answer
38 views
Local boundary symmetrisation of Riemannian metrics by coordinate changes
Assume we have a smooth Riemannian metric $g$ on a small one-sided neighborhood $U$ of $0$ on the plane, say $U_\epsilon=\lbrace(x, y): x^2+y^2<\epsilon, y\geq 0\rbrace$.
When …
3
votes
0answers
31 views
Simultaneous Linear System
Given a n-by-n matrix $\mathbf{\phi}$ and a vector $\mathbf{X}$, solve for the two vectors $\mathbf{\Phi}$ and $\mathbf{\Omega}$ that satisfy:
$$
\Phi_i = \sum_{l} \frac{\phi_{il} …
8
votes
1answer
776 views
What is Kirillov’s method good for?
I am planing to study Kirillov's orbit method. I have seen Kirillov's method in several branch of mathematics, for instance, functional analysis, geometry, .... Why is this theory …
1
vote
0answers
39 views
Irreducibility of the trinomial over Q
I'm trying to find an algebraic proof of irreducibility of the polynomial $x^n-x-1$ over rational numbers (or integers, which the same). I've read the Selmer's paper "On the irredu …
7
votes
1answer
230 views
what is the cyclic cover trick?
What do people mean by the "cyclic cover trick"? I have found this expression a couple of times with no complete explaination, both talking about curves and surfaces...
1
vote
1answer
71 views
Lower Degree Elements in an Algebraic Number Field
Fix an algebraic integer $\alpha$ of degree $n$
such that the extension $K=\mathbf{Q}(\alpha)/\mathbf{Q}$ has intermediate fields.
(We can assume $K$ is Galois with non-simple Gal …
1
vote
0answers
19 views
Upper semicontinuity of Betti numbers of submodules
Theorem 8.29 in "Combinatorial commutative algebra" by Miller and Sturmfels states the upper-semicontinuity property for Groebner deformations (say, over an algebraically closed fi …

