3
votes
0answers
44 views

Polynomials connected with Gale's condition and cyclic polytopes

I was reading about cyclic polytopes and (I think naturally) became interested in polynomials $f(X) \in \mathbb{R}[X]$ which have a factorization of the form $f(X)=g(X)g(X+1)$ for some $g(X) \in ...
2
votes
2answers
136 views

What is an extragradient method?

I've searched Google, but it seems that only research journal papers appear in search results, where some new, improved, or specialized extragradient method is discussed. I've also searched Wikipedia ...
0
votes
0answers
56 views

reference help indecomposable representations of SL(2,R)

Let $\mathfrak{g}$ be the Lie algebra $\mathfrak{sl}_2(\mathbb{C})$, $K=SO(2)$ the maximal compact subgroup of $SL_2(\mathbb{R})$. Then the classification of irreducible admissible ...
1
vote
0answers
45 views

symmetric theta structures and arithmetic subgroups

A symmetric theta structure is a theta structure that commutes with (a lift of) the natural involution $\imath: A \to A$ an an abelian variety. For simplicity I will assume that $A$ is a surface. ...
0
votes
1answer
75 views

A special class of random variables

I'm interested in classes C of $R^1$-valued random variables which possess the following properties: 1) the sum of two independent random variables from class C belongs to class C; 2) for any ...
2
votes
1answer
83 views

How can I prove that the negative biased triangular kernel is positive semidefinite

How can I prove that the following triangular kernel function defined in $[0, 1] \subset R^1$ $k(x, x') = (1 - 2|x-x'|)$ is a positive semidefinite function? It turns out to be psd function when ...
0
votes
0answers
57 views

A certain Acyclic Partition of a digraph

Has the following object been defined in the literature? What is it called? And what literature studies it? Are there other characterizations of this? What properties are known? Let $G$ be a directed ...
3
votes
0answers
46 views

Assumption of equal prior message probabilities in the standard proofs of the converse of Shannon's theorem

One of the first steps in the standard proofs for the (weak) converse of the Shannon's theorem (a.k.a. noisy-channel coding theorem) for the discrete memoryless sources is the assumption that messages ...
2
votes
1answer
166 views

What does the defect of a block measure?

In the context of decomposition matrices for Hecke algebras of finite Coxeter groups at a root of unity (such as the tables at the end of the book "Hecke algebras at a root of unity" by Geck-Jacon or ...
2
votes
1answer
172 views

Classes in $H^3(G; \mathbb{Z})$ that restrict to zero on abelian subgroups

Let $G$ be a finite $p$-group. Is it possible to have a nonzero class in $H^3(G; \mathbb{Z})$ that restricts to zero in $H^3(A; \mathbb{Z})$ for every abelian subgroup $A \subset G$? If so, what is a ...
2
votes
2answers
102 views

Invariant planes of a nilpotent matrix with two Jordan blocks of size two

Describe all the invariant 2-dimensional subspaces of $\mathbb{C}^4$ (or $\mathbb{R}^4$) of the nilpotent map $$ N = \begin{pmatrix} 0 & 1 & & \\ 0 & 0 & & \\ & & 0 ...
6
votes
2answers
288 views

Twist in identification with singular cohomology

Let $X$ be a smooth projective variety over $\mathbb{Q}$ and $$V = H^m(X(\mathbb{C}), \mathbb{Q} \cdot (2\pi i)^r)$$ Then I've seen people write the comparison with complex cohomology (an isomorphism ...
1
vote
1answer
63 views

Algorithm for Polynomial Reduction in a Quotient Ring

Any reference or suggestion for the following problem would be greatly appreciated. I am working on the quotient ring $Q=R[X_1,\dots,X_n]/<f_1,\dots,f_k>$. Given polynomials $p$ and $q$ I want ...
4
votes
1answer
89 views

When are the congruence lattices nicer?

This is a purely idle question, but one I'm increasingly interested the more thought I put into it: For $\mathcal{A}$ a universal algebra (that is, nonempty set together with some named functions), a ...
-1
votes
1answer
53 views

Solution to simple first-order partial differential equations [on hold]

Is there a general solution for first-order partial differential equations of the form $$m(x) \partial_x f(x,y) = n(y) \partial_y f(x,y)$$ for given $m(x),n(y)$ and reasonable boundary conditions ...
0
votes
0answers
161 views

PBW proof proposal

One version of the PBW theorem states: $\omega $:$\mathfrak {S} \mapsto \mathfrak {E} $ is an isomorphism of algebras. I am curious if this is a possible proof for the PBW theorem, part is taken ...
0
votes
0answers
24 views

Equivalence of ordered field and an order relation [on hold]

I found this theorem in 'Set Theory and Structure of Arithmetic by Hamilton and Landin' A field K is an ordered field with respect to a subset P if and only if there is a binary relation < on K ...
3
votes
1answer
371 views

Existence of finite nonabelian groups satisfying certain identities

Is there a finite nonabelian group satisfying all of the following identities? $$ (x^py^p)^2 = (y^px^p)^2, \quad p = 2,3,5,7,11,\ldots (\text{primes}) $$ I thank you all in advance.
2
votes
1answer
107 views

Lp estimate for resolvent of Laplace operator

Consider for $1<p<\infty$ operator $A_p:L_p(0,1)\to L_p(0,1), \ D(A_p)=\{u\in W^2_p(0,1): u'(0)=u'(1)=0\}, \ A_pu=u''$, i.e. $L_p$-realisation of the Laplace operator with Neumann bcd on the ...
3
votes
1answer
68 views

$\mathcal{H}$-polyhedron under a linear map

Let $P = \{ x \in \mathbb{R}^n \mid Ax \leq b \}$ be a (bounded) polyhedron for $A \in \mathbb{R}^{m \times n}$ and $b \in \mathbb{R}^m$, $n,m > 0$. Moreover, let $M \colon \mathbb{R}^n \to ...
0
votes
0answers
109 views

Hermitian metric on $f_*(\Omega_{X/X_{can}}^{n-k})$

Let $X$ be an n- dimensional algebraic manifold . Suppose that its canonical line bundle $K_X$ is semi-positive and $0<k=Kod(X)<n $ . Let $f: X\to X_{can}\subset \mathbb CP^N$ Here $X_{can}$ ...
1
vote
0answers
130 views

open problems in Numerical Analysis [on hold]

There are plenty of open problems in Graph Theory, Number Theory, and Combinatorics, according to the Open Problem Garden: http://www.openproblemgarden.org/. Yet there are no open problems in ...
2
votes
0answers
55 views

If the generating function summation and zeta regularized sum of a divergent exist, do they always coincide?

One could assign a value to divergent series by means of several summation methods. One summation method we could consider is the generating function method. Let's sum, for example, the fibonacci ...
0
votes
0answers
65 views

uniform continuity of a function in ultrametric spaces

Consider $[0,1]$ with the metric $d_1(x,y)=\left\{\begin{array}{cc} 0&x=y,\\ \max\{x,y\}&x\ne y. \end{array}\right.$. Moreover let $(M,d_2)$ be an ultrametric space. Let ...
-3
votes
0answers
63 views

How to solve the definite integral? [on hold]

the integrate is as follow: integrate[ln(1+x^2)/(1+x)],{x,0,1} Thank you!
0
votes
0answers
21 views

null space of a specific 4x4 symbolic matrix [migrated]

I need to find the symbolic null space vector (let's call it X ) of a symbolic matrix: ...
11
votes
1answer
181 views

Is a generic closed orientable hyperbolic 3-manifold Haken?

My question is as follows: "Is a generic closed orientable hyperbolic 3-manifold Haken?" Of course the word 'generic' can be interpreted in many ways, and the answer might depend on the way how one ...
2
votes
0answers
300 views

Help with my research topic [on hold]

I have a masters degree in mathematics and I'm currently a PHD student. Since the beginning of my studies (2 years ago) I haven't progressed and still don't have a research topic. I was a very good ...
1
vote
0answers
73 views

Laplacian mapping on various function spaces

I have a question related to a certain elliptic operator on $R^N$ but I think i can clarify my confusion if I just consider the Laplacian $\Delta$ on the unit ball in $R^N$. If $ 1 <p< ...
3
votes
0answers
107 views

Ultracoproducts of C(X)-algebras

Let $X$ be a metrizable compact topological space, let $\mathcal U$ be an ultrafilter, and denote by $X^{\mathcal U}$ the ultracopower of $X$ with respect to $\mathcal U$. As a C$^*$-algebraist, I ...
2
votes
0answers
45 views

How to prove that all smooth vector bundles on a given vector bundle are the pull back of a vector bundle on the base [migrated]

Recently, during a conversation, I heard about the result (previously mentioned also here on MO), whose statement is reported below. Not having the specific background necessary to reconstruct a proof ...
-1
votes
0answers
167 views

Where is the Flaw in the Argument? [on hold]

Some days ago I have read about the Legendre Symbol. I found that there is no easy method for computation of the symbol. I tried to find out a method for determining the value of ...
2
votes
1answer
190 views

A family Mersenne composite numbers?

I believe that the number $$2^{2^{2t+1}+2t-1}-1$$ is composite for all positive integer $t$. I tested this for many $t$'s, but so far I didn't get a proof. Any idea?
3
votes
3answers
98 views

Basic Questions about Radon Transforms

I am currently working on a problem that may be interpreted as recovering an unknown function from its Radon transform. Unfortunately I don't have any background in Radon transform, but need to ...
2
votes
1answer
109 views

what is the stabilization of pointed sets?

Given a(n $\infty$-)category, there is a process called "stabilitazion" which spits out a stable $\infty$-category (as one can read about in either Higher Algebra or the nlab). The famous example is ...
1
vote
0answers
74 views

On the computation of Asai L-function

I want so compute some simple twisted Asai L-function. Let $E/F$ be a quadratic extemsion of number fields and $v$ a finite place of $F$. Let $\chi$ be a unitary automorphic character of ...
8
votes
1answer
179 views

Second homology of mapping class group of genus 3

In a survey paper of Korkmaz it is stated that $H_2(\mathrm{Mod}_3)$ is either $\Bbb Z$ or $\Bbb Z \oplus \Bbb Z_2$, but I was not able to find out a precise computation of this group (resolving the ...
2
votes
1answer
76 views

Characteristic polynomials of reductive subgroup over C

Can any one provide a hint to prove the following statement? : Let $H$ be a complex reductive subgroup (not necessarily connected) contained in $SO(n,\mathbb{C)})$. Consider the map $H \rightarrow ...
2
votes
0answers
119 views

Metric on the set of subsets of the rational primes

I was thinking how to say that two sets of prime numbers are close to each other, and came up with this. NOTATION $\ \Delta(A\ B)\ :=\ (A\setminus B)\cup(B\setminus A)\ \ $ is the symmetric ...
9
votes
1answer
221 views

Repetend digit graphs for $1/n$ in base $b$

Here is a decimal expansion of $\frac{1}{34}$: $$(1/34)_{10}=0.02941176470588235\overline{2941176470588235}\ldots$$ And here is a graphical representation of the 16-digit "repetend," as a directed ...
-1
votes
0answers
56 views

How to find number of nonisomorphic simple graphs from a number of edges and a number of vertices? [on hold]

How many nonisomorphic simple graphs are there with __ vertices and _ edges? (Fill in the blanks with numbers, say 6 and 4) I've tried to use incident matrices to no avail.
6
votes
1answer
207 views

Rational points techniques on curves not using their Jacobian

Let $C/K$ be a curve of genus > 2 over a number field $K$ and suppose there exists a $p \in C(K)$. Then a recurring theme in studying $C(K)$ is using the map $C \to J(C)$ normalized by sending $p$ to ...
0
votes
0answers
58 views

irreducibility of $x^m-g(y)$

Let $g(y)\in \mathbb{C}[y]$, $ m\in \mathbb{Z}_{ge 2}$. Is there some results on the irreducibility of $x^m-g(y) in $\mathbb{C}[x,y]$?
-7
votes
0answers
292 views

Why Adrian Vasiu did not get the fields medal? [on hold]

Why Adrian Vasiu, brilliant as a mathematican, is socially unpopular at the mathematical society? Why he did not get the fields medal?
2
votes
0answers
97 views

A question on resolution of singularities

I am wondering if it could be possible in particular cases to resolve a singularity of dimension $n$ by blowing-up a locus of dimension smaller than $n$. For instance consider a cubic surface ...
10
votes
1answer
421 views

Time in Girard's Geometry of Interaction

Jean-Yves Girard writes at the end of his paper "Towards a Geometry of Interaction", page 105, that we have three intuitions about the nature of time: time is logic modulo the order of rules, time ...
4
votes
1answer
132 views

Estimates on derivatives of Bessel function

In Duke, Friedlander and Iwaniec's Erratum on "Bounds for automorphic L–functions. II" They have the following estimates for derivatives of Bessel functions: For $k \geq 2$ \begin{align} & ...
1
vote
1answer
58 views

Real solutions for systems of monomial equations

I have a $K$ equations of the form $x_1^{a_{i1}} \cdots x_n^{a_{in}}=c_i$ where $a_{ij}$ are non-negative integer constants and $c_i$ are real constants -- i.e. each equation is a monomial in $n$ ...
2
votes
1answer
55 views

Separating Differences of Open Sets

Has anyone ever considered something like the following separation axiom? $(*)$ For any pair of open sets $O$ and $N$, there exist disjoint open sets containing $O\setminus N$ and $N\setminus O$. ...
-1
votes
0answers
105 views

Primality matrices [on hold]

This question is some kind of a follow-up to my previous thread untitled About Goldbach's conjecture, the content of which follows: 'let's consider a composite natural number $n$ greater or equal ...

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