Newest Questions
159,064 questions
12
votes
0
answers
543
views
Does Wedderburn's Little Theorem hold constructively?
Wedderburn's Little Theorem states that every finite division ring is commutative. Perhaps even more surprising, this implies that every finite reduced ring is commutative.
The proofs that I am aware ...
- 63.1k
4
votes
1
answer
322
views
If $P\times{\bf2}$ order-embeds in $Q\times{\bf2}$, does the poset $P$ embed in the poset $Q$?
A function $f:P\to Q$ from a poset $(P,\le_P)$ to a poset $(Q,\le_Q)$ is an order-embedding if, for all $p,p'\in P$, $p\le_P p'$ if and only if $f(p)\le_Q f(p')$.
We partially order the Cartesian ...
- 1,644
1
vote
0
answers
64
views
How to find all linear transformations commuting with all elements of the image of an isotypic representation of a compact Lie group
Let a linear finite-dimensional isotypic (i.e., decomposable into a direct sum of isomorphic irreducible subrepresentations) representation of a compact Lie group $G$ in a finite-dimensional space $V$ ...
- 309
15
votes
2
answers
1k
views
Positive quadratic polynomial
Let $S$ be solutions of a system of quadratic polynomials on $\mathbb{R}^n$.
Suppose $q$ is another quadratic polynomial such that $q|_S\geqslant 0$.
Is it possible to find a polynomial $\tilde q$ ...
- 45k
3
votes
1
answer
337
views
Closed-form expression for definite integrals involving modified Bessel functions K_1 and K_0
I am attempting to derive a closed-form expression for the following two integrals involving the modified Bessel functions $K_1$ and $K_0$, but I can't find a solution (I don't know if there is one). ...
- 43
12
votes
1
answer
642
views
Is the appearance of Schur functions a coincidence?
The Schur functions are symmetric functions which appear in several different contexts:
The characters of the irreducible representations for the symmetric group (under the characteristic isometry).
...
- 193
13
votes
1
answer
387
views
Realizing integral homology classes on non-orientable manifolds by embedded orientable submanifolds
Let $M^m$ denote a compact, non-orientable smooth manifold and $\nu$ an integral homology class of dimension $n$. I am interested in understanding the representability of $\nu$ by embedded, orientable ...
- 587
7
votes
2
answers
1k
views
MIP*=RE theorem and its impact on logic and proof theory
In the monumental paper MIP*=RE five authors, Zhengfeng Ji, Anand Natarajan, Thomas Vidick, John Wright, and Henry Yuen, managed to show that two complexity classes: RE and MIP* do in fact coincide. ...
- 9,340
0
votes
0
answers
164
views
How to prove negativity of a $3\times3$ determinant whose elements involve trigamma, tetragamma, and pentagamma functions?
The classical Euler gamma function can be defined by the integral
\begin{equation*}
\Gamma(z)=\int_0^{\infty}t^{z-1}\operatorname{e}^{-t}\operatorname{d}t, \quad \Re(z)>0.
\end{equation*}
Its ...
- 1,101
3
votes
0
answers
200
views
Contractibility of the pseudo-boundary of the Hilbert cube
Let the separable Hilbert cube $Q=\prod_{i=1}^{+\infty}[0,1]$ embed into the real Hilbert space $H=l^2(\mathbb{Z}^+)$, whose coordinate unit vectors are $\{ e_i \}_{i=1}^{+\infty}$, as the subset $\...
- 1,543
2
votes
0
answers
105
views
Geometrizing saturation construction
Edit: My original question quickly got one close request, so I edited it to add some context and motivation.
Consider homogeneous polynomials $J_1,\dots,J_r\in k[\bar x]$. I want to construct a ...
- 650
1
vote
1
answer
187
views
Question of pole and zeros of symmetric or exterior global $L$-function of $\mathrm{GL}_n(\mathbb{A})$
Let $\pi$ be a unitary cuspidal representation of $\mathrm{GL}_n(\mathbb{A})$.
It is written is some paper that using the results towards the generalized Ramanujan conjecture in the paper "On the ...
- 1,019
23
votes
1
answer
2k
views
Does this expression always vanish?
I have checked that the following expression
\begin{align}
\sum_{i=1}^N\sum_{j=1\\
j\ne i}^N\frac{A_iA_j(A_i+A_j)}{(A_i-A_j)^3}\prod_{k=1\\
k\ne i\\
k\ne j}^N\frac{A_i A_k}{(A_i-A_k)^2}
\end{align}
is ...
- 341
1
vote
0
answers
124
views
Question on the Rankin-Selberg epsilon function
Let $\pi$ and $\pi'$ be unitary cuspidal automorphic representation of $\mathrm{GL}_n(\mathbb{A})$ and $\mathrm{GL}_m(\mathbb{A})$, respectively.
It is well known that the complete Rankin-Selberg $L$-...
- 1,019
2
votes
1
answer
275
views
Does this KL divergence inequality hold?
Suppose $p$ and $q$ are two discrete distributions. Given a positive constant $\beta\in(0,1)$, we create a new discrete distribution $y$ such that
$$
\frac{y\left( x \right)}{p\left( x \right)}=\frac{\...
- 49
1
vote
0
answers
110
views
Improved conjecture about partitions of the powerset without the empty set
This conjecture is similar to the previously disproved one, but more difficult.
For any partition $\mathcal{F}=\{\mathcal{A_1},\ldots,\mathcal{A_m} \}$ of the powerset without the empty set element $\...
- 700
1
vote
0
answers
76
views
Analytical solution to coupled ODEs arising in molecular evolution
The following system of coupled ODEs arises in the study of DNA sequence evolution:
\begin{eqnarray*}
\frac{da}{dt} & = & \frac{\mu (1-y) b u}{S - y(S-b-v)} - (\lambda +\mu ) a \\
\frac{db}...
- 19
1
vote
0
answers
162
views
Motivic complex on arithmetic schemes
If we believe the finite generation of motivic cohomology for regular arithmetic schemes like $X$ then we can see that (using Quillen-Lichtenbaum)for infinitely many primes $l$ we have an isomorphism ...
- 5,901
2
votes
0
answers
292
views
Tate's conjecture for arithmetic schemes
Tate's conjecture is about a map from Chow groups of a smooth projective variety $X$ to the $l$-adic cohomology i.e. $CH^n(X)\rightarrow (H^{2n}(\bar{X}, \mathbb{Q}_l(n)))^G$ where $G$ is the Galois ...
- 5,901
2
votes
0
answers
56
views
Is there a Fokker-Plancker analogue for the joint distribution of $(X_t, X_{t+\Delta t})$?
Let $X$ be the solution to (real-valued) stochastic differential equation :
$$dX_t = b(t,X_t)dt + a(t,X_t)dW_t, \quad \forall t\ge 0.$$
Let $\Delta t>0$ be given. Under suitable conditions (on $b,a,...
- 1,399
6
votes
1
answer
264
views
Existence property for second-order propositional logic
Consider the intuitionistic second-order propositional calculus (SOL) formulated in the full $\wedge,\vee,\rightarrow,\bot,\top,\forall,\exists$ language.
Question: Assume that $\Gamma$ and $\Psi$ are ...
- 756
2
votes
0
answers
140
views
Strong converse of Kazhdan's property (T)
In his 1972 paper Sur la cohomologie des groupes topologiques II, Guichardet proved$^\ast$ that (non-abelian) free groups satisfy the following strong converse of property (T): The $1$-cohomology $H^1(...
- 1,027
3
votes
1
answer
423
views
Factorizations of cyclotomic polynomials valuated at primes
I have a question concerning cyclotomic polynomials valuated at primes. I first state it in the easiest possible form.
There exists a function $f:\mathbb{N}\to\mathbb{N}$ such that, if $p$ is a prime, ...
- 934
3
votes
0
answers
192
views
Hodge symmetry without $\mathbb{C}$ [duplicate]
If $k$ is a field of characteristic zero and $X$ is a smooth irreducible projective variety over $k$, then $X$ satisfy Hodge symmetry, meaning that
$$\dim H^p(X, \Omega_{X/k}^q) = \dim H^q(X, \Omega_{...
- 3,446
5
votes
1
answer
138
views
Does the bicategory of additive categories admit bicolimits?
By bicolimit I mean what Kelly means in its "Elementary observations on 2-categorical limits". If we have a diagram (pseudofunctor) $G\colon\mathcal P\to\mathcal K$, the bicolimit of $G$ is ...
- 351
4
votes
1
answer
518
views
Probability to return to the origin for a uniform random walk
Consider a uniform random walk on $\mathbb{R}$, with stepsize chosen uniformly from the interval $(-1,1)$. The random walk start at $x=0$. Denote by $\rho_p dx$ the probability that the random walk ...
- 188k
11
votes
1
answer
390
views
Does every finite affine plane have the doubling property?
Definition 1. An affine plane is a pair $(X,\mathcal L)$ consisting of a set $X$ and a family $\mathcal L$ of subsets of $X$ called lines which satisfy the following axioms:
Any distinct points $x,y\...
- 42k
2
votes
0
answers
435
views
Generalized conjugacy classes in (topological) groups
Let $G$ be a topological group. We define an equivalence relation on $G$ as follows:
For $a,b\in G$ we set $a\sim b$ if the following two maps are topologically conjugate:
$$x\mapsto ax,\qquad x\...
- 366
3
votes
0
answers
201
views
When is the albanese map an embedding
Let $S$ be a surface defined over a field $K$, when is the albanese map $S\longrightarrow \text{Alb}(S)$ an embedding?
For curves, for example, with genus at least 2, there is a morphism between the ...
- 2,907
2
votes
1
answer
233
views
Completely contractive Banach algebra structure on the dual of a Hopf $C^*$-algebra
Let $(A, \Delta)$ be a Hopf $C^*$-algebra, i.e. $A$ is a $C^*$-algebra, and $\Delta: A \to M(A\otimes A)$ is an injective non-degenerate $*$-homomorphism that is coassociative:
$$(\iota \otimes \Delta)...
- 175
1
vote
0
answers
47
views
How to get perturbation bounds of singular vectors
Let an adjacency matrix $A={A^\top}\in {\mathbb{R}^{n \times n}}$ (a binary matrix) of a simple undirected graph and its degree matrix $D$ be given.
When adding $Q$ edges into the graph, which is ...
- 11
0
votes
0
answers
81
views
Is there is a constant $c$ such that toroidal graphs are minor-$c$-colorable?
A toroidal graph is a graph that can be embedded on a torus. In other words, the graph's vertices can be placed on a torus such that no edges cross.
A minor of graph G is a graph obtained from G by ...
- 1,190
1
vote
0
answers
119
views
Computing $G$-theory for a 3-dimensional affine simplicial toric variety
Let $k$ be an algebraically closed field of characteristic zero. Let $\sigma$ be the cone in $\mathbb{R}^3$ generated by $e_1,2e_1+e_2,e_1+2e_2+3e_3$.
Then it is easy to check that $\sigma$ is a 3-...
- 639
6
votes
0
answers
253
views
Are bounded groups of thin operators on Hilbert space similar to groups of unitaries?
QUESTION. Let $G$ be a group of bounded operators on $\ell^2$, satisfying $\sup_{x\in G} \lVert x\rVert <\infty$, whose elements are all of the form "identity+compact" (sometimes called &...
- 25.8k
2
votes
0
answers
200
views
On the inequality-integer system [closed]
I need to prove this inequality, but I do not have a good background in algebra, if you can guide me:
We have:
$$
p_1 + 2p_2 + \ldots +kp_k < q_1 + 2q_2 + \ldots +kq_k+(k+1)q_{k+1}+\ldots+tq_t
$$
...
0
votes
2
answers
239
views
Computing the expectation of a quadratic matrix form involving Bernoulli and Gaussian distributed matrices
I am working with two random matrices, $Z$ and $H$:
$Z$ is an $n \times K$ matrix with entries sampled i.i.d. from a Bernoulli distribution: $Z_{ij} \sim \mathrm{Bernoulli}(p)$.
$H$ is a $K \times K$ ...
- 37
2
votes
1
answer
150
views
Sufficient conditions for the graph measurability of a multivalued function
I am currently working on a problem related to the measurability of multi-functions in the context of mathematical economics. Specifically, I am searching for sufficient conditions regarding the graph ...
- 79
8
votes
1
answer
205
views
Connectivity of the space of transverse vector fields
Suppose we have a smooth, closed manifold $M$ of dimension $n$ and connectivity $k$. What can we say about the connectivity of the space of all tangent vector fields on $M$ that are transverse to the ...
- 2,062
1
vote
0
answers
158
views
Initial conditions to falsify Rowland's conjecture
Based on the Rowland's paper (A natural prime-generating recurrence), is there any theorem to show that for which initial condition $a(1) = k$ the conjecture can be falsified?
For example, for $k$ ...
- 151
2
votes
1
answer
225
views
Restrictions of affinoid functions from wide open neighbourhoods
Let $X=\operatorname{Sp}(A)$ be an affinoid $K$-space, where $K$ is a p-adic field. Suppose that $X$ lies in the interior of another affinoid $K$-space $X'=\operatorname{Sp}(B)$. Recall that this ...
- 117
3
votes
0
answers
87
views
Bounding the degree of the Weierstrass polynomial of a product of a holomorphic function and a polynomial
In brief. For a fixed holomorphic function $v$, I want to bound the degree $q$ of the Weierstrass polynomial $Q$ in the Weierstrass decomposition $v^TP = uQ$, in terms of the degree $p$ of the ...
- 981
1
vote
0
answers
51
views
Hardness of an optimization problem when some variables are fixed
Given a general optimization problem, I would like to know what we can say about the hardness of the problem when a subset of its variables are fixed.
With the two (related) examples, it is clear that ...
- 11
0
votes
0
answers
162
views
Gluing faces of n-cube
Assuming $C_n$ be the $n$-cube, the intersection of $C_n$ with a supporting hyperplane $H(P, v)$ is called a face or more precisely a $d$-face if the dimension is $d$.
Let $f_0$ and $f_1$ be faces ...
- 53
2
votes
0
answers
46
views
Size of set of positive integers no sum of two distinct elements giving square
Question: find the size of a maximal subset $A$ of $[n]=\{1,\cdots,n\}$ satisfying that for any distinct elements $x,y\in A$, $x+y$ is not a perfect square.
Consider a graph with $n$ vertices: $x$ and ...
- 909
8
votes
0
answers
443
views
Sheaf of compact Hausdorff spaces but not a condensed anima
Consider the site $\mathbf{CHaus}$ of compact Hausdorff spaces together with the finitely jointly surjective families of maps as coverings. Restriction induces an equivalence of categories $$ \mathbf{...
- 435
1
vote
1
answer
132
views
A non-example of a graded Frobenius algebra
Take the class of finite dimensional graded algebras $A = \sum_i A_i$ satisfying $|A_n| = 1$ where $A_n \neq 0$ and $A_m = 0$, for all $m > n$. What is an example in this class that is not ...
2
votes
0
answers
180
views
Approximating $L^p$ functions by eigenfunctions of Laplacian
I'm reading a paper https://www.sciencedirect.com/science/article/pii/S0022039608004932.
In this paper, the authors assume that $\mathcal{O}$ is a bounded domain of $\mathbb{R}^N$ with $C^m$ boundary ...
- 121
2
votes
1
answer
247
views
On Dirac/ Clifford matrices
Let $(\eta^{\mu\nu})=\operatorname{diag}(+1,-1,-1,-1)$.
The Dirac matrices $\gamma^\mu$, $\mu=0,1,2,3$ satisfy by definition
$$\{\gamma^\mu,\gamma^\nu\}=2\eta^{\mu\nu}\tag{1}\label{1}$$
where $\{A,B\}=...
- 21.8k
5
votes
0
answers
373
views
A (possible) Lie algebra extension of the Lie algebra of a foliation
Motivation: The aim of this post is to extend the Lie algebra of a foliation to a bigger Lie algebra. We assume that a manifold $M$ is foliated by compat leaves. The Lie algebra of the foliation is ...
- 366
2
votes
0
answers
54
views
Finite (schema) axiomatizability of representable cylindric algebras
If we know that the class of all representable cylindric algebras of dimension $\alpha$ (for any ordinal number $\alpha>2$) is NOT finitely (schema) axiomatizable*, then does it (perhaps trivially) ...
- 63