# All Questions

**-1**

votes

**0**answers

11 views

### normal groups of a nonabelian p-group

Let $G$ be a finite nonabelian $p$-group.
For any $x\in G$ such that $x^{p}=1$, does there exist a normal subgroup $N$ of $G$ such that $x\not\in N$?

**0**

votes

**0**answers

9 views

### Explicit representation for algrebra of smooth functions on a manifold

Suppose we have some smooth manifold $M$. Space of its smooth functions $C(M)$ is an algebra, and as far as I understand, it is $C^*$-algebra by trivial involution.
Every $C^*$-algebra has a ...

**0**

votes

**0**answers

10 views

### Generating $\mathfrak{so}(7)$

Short version: Let $V$ be a 7-dimensional linear space of (real) square matrices. Suppose further that $[V,V]$ (the linear space spanned $[X,Y]$, $X,Y\in V$) is isomorphic to $\mathfrak{so}(7)$. Can ...

**0**

votes

**0**answers

16 views

### 4-D lattices and quaternion

It is easy to prove that there are only 2 extensions $\mathbb{Q}(a)$, with $|a|=1$, of $\mathbb{Q}$ where $\mathbb{Z}[a]$ becomes a lattice(discrete free abelian subgroup of rank 2) in the complex ...

**0**

votes

**0**answers

6 views

### algorithms to solve convex problems

which algorithms are used to solve convex / SOCP problems? for instance, which numerical algorithm is implemented in Sedumi or cvxgen? interior-point methods, or something else?
Thanks

**3**

votes

**0**answers

23 views

### Extending the topology on a set to the group/vector space it generates

The multiplicative group $\Bbb Q^+$ can be viewed as a $\Bbb Z$-module. To see this, note that any rational can be decomposed into the form
$2^{n_2} \cdot 3^{n_3} \cdot 5^{n_5} \cdot ...$
The tuple ...

**1**

vote

**0**answers

28 views

### Relation between crystalline and perverse sheaves

Take $X$ to be a smooth complex projective algebraic variety. The Riemann-Hilbert correspondence gives an equivalence of categories between the category of perverse sheaves on $X$ and the category of ...

**0**

votes

**0**answers

26 views

### Mathematical Definition of $n$-Brouillin Zone [duplicate]

I am having trouble finding a mathematical definition of the Brouillin zone beyond the first, which are basically the Voronoi cells or Wigner-Seitz cells. We could imagine the set of point closer to ...

**0**

votes

**0**answers

22 views

### A certain measure on $C^{*}$algebras

Is there a reference who introduce the following measure on a $C^{*}$ algebra and investigate it from the view point of $C^{*}$ algebra or from the view point of ergodic theory?:
Let $A$ be a $C^{*}$ ...

**3**

votes

**0**answers

31 views

### Equivalence of questions regarding restrictions of pure states

In Davidson and Szarek's article "Local Operator Theory, Random Matrices and Banach Spaces" in the Handbook of the Geometry of Banach Spaces, the authors discuss the (now solved) Kadison-Singer ...

**3**

votes

**2**answers

315 views

### Statements going against the grain of Riemann Hypothesis (R.H.)

Let $M(N) := \sum_{n=1}^N \mu(n)$
It is known that bounding $M(N)$ by $N^{1/2+\epsilon}$ implies R.H.
A bound of $M(N)$ by $K\sqrt N$ for say $ K\ge2 $ is also sufficient. $K = 1$ is excluded as ...

**0**

votes

**0**answers

21 views

### Solving for f given constraint involving f(x, y) and f(xy, y)

I am interested in a weighted version of the Catalan numbers. The generating function for this case,
$$ f(x, y) = \sum_s \sum_n f_{s n} x^s y^n $$
(where the $y^n$ term is the weight), obeys the ...

**5**

votes

**1**answer

148 views

### Power sums of p-th roots of unity

The following question was asked by a colleague of mine. For any prime $p$ consider
$$ M_p:=\min_{z_1,\dots,z_p}\max_{j,k}\left|z_1^k+\dots+z_j^k\right|,$$
where $z_1,\dots,z_p$ are the complex $p$-th ...

**0**

votes

**1**answer

80 views

### Spectral sequences to compute Hom's in derived category

Does anybody have a good reference that lists spectral sequences that may be used to compute Hom sets in derived categories (of coherent sheaves, say)?

**1**

vote

**0**answers

37 views

### Explicit construction of a bielliptic curve

Let $C$ be a (projective smooth complex) curve such that $K_C=2(D+p)$, with $D+p$ defining a $g_7^2$; $p$ is a base point and $D$ defines a 2-to-1 map $\varphi:C\rightarrow E\subset\mathbb{P}^2$ onto ...

**0**

votes

**1**answer

59 views

### Is there currently a known way to construct an injective mapping that transforms finite graphs into discrete geometric objects?

If there is such a mapping, it seems as though it could turn the graph isomorphism problem from a purely combinatorial problem to a discrete geometric one.

**0**

votes

**0**answers

66 views

### In commutativity theorems in ring theory

Suppose that $R$ is a ring such that for any $x\in R$ there exists $1<n(x)\in \mathbb{N}$ such that $x^{n(x)}-x\in Z(R)$. Prove that $R$ is commutative or if it is not commutative, then the ideal ...

**4**

votes

**0**answers

52 views

### What is know about maps between loop spaces of Spheres? - Reference request

What is know in general about the maps $\Omega^rS^n\rightarrow\Omega^sS^m$ between loop spaces of Spheres, or, perhaps to phrase it better, the groups $[\Omega^rS^n,\Omega^sS^m]$ for various values ...

**1**

vote

**0**answers

24 views

### Sufficient condition for the unique solvability of Dirichlet problem of Hamilton-Jacobi equation

It shall be an old story in PDE.
I am looking for a sufficient condition of Dirichlet problem for the existence of the unique viscosity solution of the equation in the form of
$$\inf_{a \in [-1,1]} \{...

**3**

votes

**0**answers

43 views

### Stabilizers of pairs of ternary quadratic forms

Let $A,B$ be two ternary quadratic forms with real coefficients, given by symmetric matrices
$$\displaystyle 2A = \begin{pmatrix} 2a_{11} & a_{12} & a_{13} \\ a_{12} & 2a_{22} & a_{23}...

**1**

vote

**1**answer

42 views

### suspension operad

There are many candidates of suspension operad in literature. Among them, $\Lambda= {\rm End}_{s\mathbb{K}}$ and $\Lambda'=\{s^{1-n}\mathbb{K}\otimes sgn_n\}_{n\geq 0}$ are typical ones. The oeprad ...

**4**

votes

**0**answers

55 views

### Is the natural isomorphism $|FX_\bullet| \cong F|X_\bullet|$ lax symmetric monoidal?

Let $\mathcal{V_1}$ and $\mathcal{V_2}$ be cocomplete symmetric monoidal categories, each endowed with a cosimplicial object $\Delta^\bullet=\Delta^\bullet_{\mathcal{V}_i}:\Delta \to \mathcal{V}_i$. ...

**1**

vote

**0**answers

153 views

### In what language do you think when doing mathemematics? [on hold]

Today, nearly all important papers are written in English. People whose mother tongue is not English nevertheless have to learn English if they want to be a mathematician. My question concerns these ...

**0**

votes

**0**answers

32 views

### Compact Embeddings [on hold]

Put:
$D=\{u\in L^{2}(\mathbb{R}^{2})| N=(x\frac{d}{dy}- y \frac{d}{dx})u\in L^{2}(\mathbb{R}^{2}) \}$
Why $D \hookrightarrow L^{2}(\mathbb{R}^{n})$ with compact injection?
Thank you in advance.

**2**

votes

**2**answers

137 views

### Reducibility of determinantal hypersurfaces

I have a determinantal hypersurface defined by $\det(A)=0$, with $a_{ij}$ homogeneous polynomial of fixed degree $d$ in $n$ variables. $A$ is not diagonal. How can I find out whether the hypersurface ...

**2**

votes

**1**answer

30 views

### upper bound on the difference between two Perron-Frobenious eigen values

Let $\lambda, \mu$ be the Perron-Frobenious eigen value of the non-negative matrices $A,B$ respectively. I am interested in knowing whether there are any results available on the upper bound of $|\...

**1**

vote

**0**answers

35 views

### When the tensor product of motives that are not $0$-(homotopy)-connective can be $0$-connective?

For $t$ being the homotopy $t$-structure for Voevodsky effective motivic complexes
when $M\otimes N\in DM_{eff}^{t\le -1}$ ensures that either $M$ or $N$ belongs to $DM_{eff}^{t\le -1}$ (so, we use ...

**0**

votes

**0**answers

36 views

### Order statistics of iid uniform RV and Pólya's urn model. Question about a.s. convergence

Let $U_1,U_2,U_3,\dots$ be IID uniform on $[0,1]$. For each $n\geq 1$ let
$$U_{1:n}<U_{2:n}<\dots<U_{n:n}$$
be the order statistic of $(U_1,\dots,U_n)$. Independent of the $U$ process there ...

**1**

vote

**1**answer

56 views

### Hyperplane generic to a given arrangement

At the moment, I am reading the paper "on the connectivity of the realization spaces of line arrangements" of Nazir and Yoshinaga.
I would like to extend their Lemma 3.2 to higher dimension. However, ...

**3**

votes

**1**answer

105 views

### A follow up question to: Number of walks on integer lattice with self-edge at zero

Let $a(n)$ be the number of lattice paths in ${\mathbb{Z}^2}$ of length $n$ which start at the origin $(0,0)$ and end up at $(n,0)$ and have only up-steps $U:(i,j) \to (i + 1,j + 1)$, down-steps $D:(...

**3**

votes

**0**answers

93 views

### Fourier Mukai transform for non-quasi coherent sheaves

Let $A$ be an abelian variety and $\hat A$ be the dual abelian variety. If $P$ is the (normalized) Poincare line bundle, then Mukai defines $R\hat S:D(A)\to D (\hat A)$ via $R\hat S(?)=Rp_{\hat A,*}(...

**0**

votes

**0**answers

70 views

### Can we use GAP to find index of subgroup of an infinite group? [on hold]

Can we use GAP to find index of subgroup of an infinite group? If yes, please tell how, I tried kgmag package of GAP but could not find. From various questions here, I guessed that in MAGMA, one can ...

**4**

votes

**1**answer

92 views

### Are there any unitary matrices which satisfy the Yang-Baxter equation which are universal for quantum computation?

Let $H$ be a finite dimensional hilbert space. Let $L:H\otimes H\rightarrow H\otimes H$ be a unitary transformation. Then the equation
$$(L\otimes I)(I\otimes L)(L\otimes I)=(I\otimes L)(L\otimes I)(I\...

**3**

votes

**0**answers

31 views

### A priori $C^0$ estimates for a semi-linear vector Poisson equation

Main Question
Consider a $C^2,H^2$ map $F:\mathbb{R}^m \to \mathbb{C}^n$ which satisfies the following equation:
$$
-\Delta F(x) + \sum_i a_i(x)\nabla_iF(x) + B(x)F(x) + |F(x)|^2F(x) = 0
$$
Here $a_i:...

**1**

vote

**0**answers

27 views

### Power spectrum of the difference of two Poisson processes with equal rates

I am studying the asymptotic properties of a dynamic a model involving the difference of two balanced Poisson processes (i.e., $\lambda_1 = \lambda_2$). I recently discovered the Skellam Distribution ...

**2**

votes

**0**answers

40 views

### How do spectrums interact with bi-Lipschitz maps?

If it makes things simple, we can just stick to bi-Lipschitz maps from $S^k \rightarrow \mathbb{R}^d$ (w.r.t geodesic distance on the sphere with the standard round metric and the $2-$norm on the ...

**0**

votes

**0**answers

55 views

### generic divisibility equation for two natural numbers [on hold]

Given two natural numbers N and B, so that N > B, is there a generic equation that contains only multiplications of N and B which can tell whether N is divisible by B?
Basically, something like a ...

**3**

votes

**2**answers

162 views

### Combinatorial interpretation for coefficients of reciprocal of power series

I've seen a number of combinatorial interpretations for the coefficients of the compositional inverse (aka reversion) of a power series. Is there a known combinatorial interpretation for the ...

**-4**

votes

**0**answers

32 views

**3**

votes

**1**answer

236 views

### Confusion regarding statement of mirror symmetry for elliptic curves

I am a little bit unsure about the mirror symmetry statement for elliptic curves; specifically, how the flipping of the Kähler and complex moduli works. Perhaps I should say at the outset, the reason ...

**1**

vote

**0**answers

27 views

### Integral of Daubechies wavelets [on hold]

For Daubechies wavelets according to this paper (above eq 19) this relation holds
$$
\int_{-\infty}^{-\infty} \phi(2x-i)\phi(2x-j)dx = \frac{1}{2} \int_{-\infty}^{-\infty} \phi(x-i)\phi(x-j)dx
$$
...

**0**

votes

**0**answers

93 views

### Number Theory Characterization Problem

Given any natural number $N = a_{n}a_{n-1}\ldots a_{1}$, let us associate to it the set $S_{N} = \bigcup_{j=1}^{n}\{(a_{j},j)\}$. We're going to define a d-self-contained number as any natural number ...

**7**

votes

**0**answers

68 views

### Homology of inverse limits over inverse systems more complicated than towers

Most textbooks discussions of homology of inverse limits of chain complexes consider only “towers,” i.e. inverse systems indexed by the natural numbers. I’d like to find a reference that explains what ...

**0**

votes

**0**answers

38 views

### Questions related to a summation of fraction equation

I am struggling the following problems. It is not ensured to solve completely because these problems are generated by myself. Particularly, I guess the second problem is very hard if we try to solve ...

**4**

votes

**0**answers

66 views

### Is there a name for groups of the form $Sp(1)^n$?

A (compact) torus is a Lie group isomorphic to the product of finitely many circles: $T^n = S^1 \times \cdots \times S^1$. Such groups are extremely important in Lie theory, Differential Geometry, ...

**1**

vote

**1**answer

100 views

### estimating binomial coefficients

There is a beautiful paper on the arXiv by Andrew Suk containing an asymptotic result about the Erdös-Szekeres convex polygon problem. I am struggling with one of the estimates he makes on page 4. He ...