2
votes
0answers
9 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
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 …
0
votes
0answers
7 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
161 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
33 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
28 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:
$$
\Phi_i = \sum_{l} \frac{\phi_{il} …
8
votes
1answer
768 views
What is Kirillov’s method good for?
I am planing to study Kirillov's orbit method. I have seen Kirillov's method in several branch of mathematics, for instance, functional analysis, geometry, .... Why is this theory …
0
votes
0answers
31 views
Irreducibility of the trinomial over Q
I'm trying to find an algebraic proof of irreducibility of the polynomial $x^n-x-1$ over rational numbers (or integers, which the same). I've read the Selmer's paper "On the irredu …
7
votes
1answer
214 views
what is the cyclic cover trick?
What do people mean by the "cyclic cover trick"? I have found this expression a couple of times with no complete explaination, both talking about curves and surfaces...
0
votes
1answer
65 views
Lower Degree Elements in an Algebraic Number Field
Fix an algebraic integer $\alpha$ of degree $n$
such that the extension $K=\mathbf{Q}(\alpha)/\mathbf{Q}$ has intermediate fields.
(We can assume $K$ is Galois with non-simple Gal …
0
votes
0answers
18 views
Upper semicontinuity of Betti numbers of submodules
Theorem 8.29 in "Combinatorial commutative algebra" by Miller and Sturmfels states the upper-semicontinuity property for Groebner deformations (say, over an algebraically closed fi …
3
votes
1answer
78 views
Aubin’s book - construction of Green’s function on compact manifold
In Aubin's book (nonlinear problems in Riemannian Geometry), starting from p. 106, it is shown that a Green's function of a compact manifold without boundary satisfies
$$G(P,Q) \l …
3
votes
1answer
132 views
Why is there no stack of $\ell$-adic sheaves on a curve?
One of the main players in the categorical geometric langlands correspondence is the moduli stack of rank n integrable connections on a complex curve. The reason for considering s …
0
votes
1answer
90 views
Numerical multivariate definite integration
I need to compute a set of multivariate definite integrals with infinite integration domain
$$\displaystyle \int_{-\infty}^{\infty} \cdots \int_{-\infty}^{\infty} f(x_1,x_2, \ldo …
4
votes
5answers
1k views
totally disconnected and zero-dimensional spaces
When do the notions of totally disconnected space and zero-dimensional space coincide? From what I gather, there are at least three common notions of topological dimension: coverin …

