Questions about the branch of abstract algebra that deals with groups.

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5
votes
0answers
48 views

Embeddings of finitely generated groups into uniformly convex Banach spaces

de Cornulier, Tessera, and Valette (Geom. Funct. Anal. 17 (2007), 770-792) conjectured that a finitely generated group $G$ with its word metric admits a bilipschitz embedding into a Hilbert space if ...
0
votes
0answers
38 views

Questions on invariant operators of finite group representations

1) Is there an equivalent of the Casimir operator for an irreducible representation of a finite group? 2) Given an invariant operator of a certain group, can I check if it is invariant under only ...
5
votes
0answers
72 views

Homology groups of Noetherian groups

Let $G$ be a Noetherian group. Is $H_n(G,\mathbb{Z})$ finitely generated? Do we know the above for the special cases $n=2,3$ even?
1
vote
0answers
95 views

Kaplansky Idempotent conjecture and Extension theory

We consider the Idempotent Kaplansky conjecture with $\mathbb{C}$- coefficients, that is $\mathbb{C}\Gamma$. Assume that $G_{1}$ and $G_{2}$ are torsion free groups which satisfies this ...
2
votes
1answer
67 views

What is the minimal girth of a cayley graph for Alt(n) in which the girth relator is not a proper power?

First, a definition: a girth relator for a Cayley graph is a word that you get by reading the edge labels along a shortest loop. The girth relator is not usually unique, though it is often unique up ...
1
vote
0answers
59 views

Symmetric spaces which are compact modulo the unipotent radical are compact

Is the following true? Let $X = G/H$ be a symmetric space of a reductive group over a p-adic field $F$. Let $X^0$ be an open orbit w.r.t. the action of the minimal parabolic $B$ of $G$. Let $U$ be ...
5
votes
1answer
194 views

Kernel of the character of congruence groups

Let $\Gamma$ be a congruence subgroup of $SL_2(\mathbb Z)$ and $\chi:\Gamma \to \mathbb{C}^*$ a character of $\Gamma$ with finite image. Is then $\ker(\chi)$ also a congruence group? If not, can ...
0
votes
0answers
56 views

Algebraic subgroup lattices [on hold]

For which groups is the subgroup lattice algebraic? Jiří Tůma has proved every algebraic lattice is an interval in a subgroup lattice. It seems there is close relation between algebraic lattices and ...
6
votes
2answers
162 views

Asymptotic density of finite abelian and solvable groups

For every natural number n, let: Gn be the number of distinct group structures with at most n elements; An be the number of distinct abelian group structures wit at most n elements; Sn be the number ...
1
vote
0answers
123 views

What's the ratio of inclusions of finite groups with a distributive lattice?

Definition: Two inclusions of finite groups are equivalent, $(A \subset B) \sim (C \subset D)$, if: $(A/A_B \subset B/A_B) \simeq (C/C_D \subset D/C_D)$ with $A_B$ the normal core of $A$ in $B$. ...
5
votes
1answer
158 views

Special linear groups contained in symplectic groups

Let $q$ be a power of prime $p$, and $n, m, k$ positive integers such that $mk=2n$ and $2\leq m<2n$. Let $\mathrm{Sp}(2n,q)$ be the symplectic group of dimension $2n$ over $\mathrm{GF}(q)$ and ...
6
votes
1answer
148 views

Duration and critical groups order in sandpile models and chip firing games

The famous chip firing game (which is closely related to sandpile models) goes like this: Place chips at the vertices of a graph. REPEATEDLY: If a vertex $v$ of degree $d_{v}$ has at least ...
4
votes
1answer
79 views

Equations and random subgroups in compact groups

Let $G$ be a compact group (I am mainly interested in the profinite case). Pick a sequence of $d$ elements (where $d$ is either finite or $\omega$) independently at random (w.r.t. Haar measure) and ...
-4
votes
1answer
163 views

A question about group topologies on $\Bbb Z$ [closed]

Let $\mathcal T$ be a group topology on $\Bbb Z$ such that the set of all neighborhoods of $0$ has a countable neighborhood base but not a finite base. And let $U$ be a neighborhood of $0$. Is there ...
4
votes
1answer
159 views

orthogonal group in characteristic 2

Let $O(2,\mathbb{Z}_2)$ be the orthogonal group of order two matrices. On $\mathbb{Z}_2$ there should exist just one odd quadratic form, hence the stabilizer subgroup $O^-$ of an odd quadratic for ...
2
votes
1answer
236 views

Is every closed subgroup of $\text{GL}_n(K[[x]])$ finitely generated?

Let $n \in \mathbb{N}$, $K$ a finite field. Denote by $K[[x]]$ the (profinite) ring of formal power series over $K$. Note that $\text{GL}_n(K[[x]])$ is a profinite group. Is every closed subgroup of ...
0
votes
0answers
75 views

Research of a reference about $G$-linearizations of line bundles on quasi-projective schemes

I am looking for some references for the following statement: Let $G$ be a linearly reductive algebraic group acting on a quasi-projective scheme $X$, over an algebraically closed field $K$. Let $L$ ...
1
vote
1answer
104 views

Successive Schur covers

Let $G_0$ be a finite group and $G_j$ a Schur cover of $G_{j-1}$ for $j=1,2,3\ldots$. Is $G_2$ equal to $G_1$? If not, will the sequence stop after finite steps in general?
2
votes
1answer
201 views

vanishing higher cohomology group for property T group?

Given a countable discrete group $G$ with Kazhdan's property (T), consider $\mathbb{C}G$ or $l^2(G)$ as a left $G$-module, then we can consider the group cohomology, Is it known that $H^n(G, ...
0
votes
3answers
135 views

Possible degrees of faithful projective representations of $\mathrm{PSL}(k,q)$ and $\mathrm{Sp}(2k,q)$ over complex numbers

Let $q$ be a prime power and $k$ a positive integer. What are the possible degrees of faithful projective representations of the projective special linear group $\mathrm{PSL}(k,q)$ (over the Galois ...
6
votes
1answer
97 views

Are countable FC-groups maximally almost periodic?

An FC-group is a group in which every element has a finite conjugacy class. A group G is said to be maximally almost periodic if there is an injective homomorphism from G into a compact Hausdorff ...
7
votes
1answer
245 views

Is there a finitely presented group with infinite homology over $\mathbb{Q}$?

Suppose $G$ is a discrete group given by finitely many generators with finitely many relations. Can the homology groups $H_i(G, \mathbb{Q})$, or equivalently $H_i(BG, \mathbb{Q})$ (topological ...
3
votes
1answer
137 views

A question on conjugacy classes of central involutions in a finite group

An involution $a$ of a group $G$ is called central if there exists a sylow $2$-subgroup $H$ of $G$ such that $a \in C_G(H)$, or equivalently if the centralizer of $a$ contains a sylow $2$-subgroup. ...
3
votes
1answer
132 views

Faithful representations of free pro-p groups

Let $p$ be a prime number, $m,n \in \mathbb{N}$, $F = F(p,m)$ be the free pro-$p$ group on $m$ generators. For which $(m,n)$ there is a continuous faithful representation (embedding) $\rho : F ...
1
vote
0answers
45 views

When polynomial GI implies polynomial (edge) colored GI?

(edge) colored graph isomorphism is GI which preserves the colors (of edges if it is edge colored). There are several reductions using transformations/gadgets of (edge) colored GI to GI. For edge ...
6
votes
1answer
202 views

Generalization of Frobenius groups

Frobenius group is a transitive permutation group on a finite set, such that no non-trivial element fixes more than one point and some non-trivial element fixes a point. In other words, if in a ...
1
vote
1answer
125 views

Infinite amenable group subfactors

Let amenable groups $\Gamma$ and $\Gamma'$. They act outerly of only one manner on the hyperfinite ${\rm II}_1$-factor $\mathcal{R}$. Question: $(\mathcal{R} \subset \mathcal{R} \rtimes \Gamma) ...
0
votes
0answers
51 views

some questions to “Extensions of groups by tree automorphisms” - Gupta&Sidki's work

Recently I have asked a question (I have deleted my question) about a paper stated in the title but I was told that I have to be more specific so I will try one more time. If someone needs ...
4
votes
0answers
99 views

Self-duality of the subgroup lattice of $G\times H$

Let $G$ and $H$ be finite groups and $\gcd(|G|,|H|)=1$. Suppose the lattice of all subgroups of $G\times H$ is self-dual. Is the lattice of all subgroups of $G$ self-dual?
2
votes
0answers
71 views

A twisted self-dual subgroup lattice

A lattice $(X,\le)$ is twisted self-dual iff it is self-dual but there is not any self-duality $f:X\to X$ with $f\circ f=1_X$. Is there any group with lattice of all its subgroups twisted self-dual?
2
votes
1answer
119 views

Classification of 2-groups with center of index 4

Can one obtain a classification of 2-groups with center of index 4, analogous to the classification of 2-groups with derived subgroup of index 4?
1
vote
2answers
95 views

on direct product of capable groups

Let $G=H\times T$ such that $H$ is 2-generated p-group of class two and $H$ be abelian p- group. We know if $H$ and $T$ are capable group, then $G$ is capable. Is the converse correct or no? i.e ...
0
votes
1answer
104 views

Existence a finite capable p-group of class two

Do there exists a finite capable p-group of class two with property: $G=\langle x, y, Z(G)\rangle$, $|x|=|y|=p^n$ , $Z(G)$ is not cyclic. $Z(G)$ is not subgroup of $\Phi(G)$, Frattini subgroup of ...
7
votes
1answer
153 views

Subgroups of Nilpotent groups with prescribed center

Let $G$ be a torsion-free, finitely-generated, nilpotent group of nilpotency class at least 3. Does there exist a normal subgroup $N\leq G$ such that $G/N\cong \mathbb{Z}$ and $Z(G)=Z(N)$? (By ...
2
votes
1answer
222 views

Can a closure make the index finite?

Let $F$ be a free finitely generated group, $H \leq F$ of infinite index. Let $c : F \rightarrow \hat{F}$ be the embedding in the profinite completion. Denote by $\tilde{F}, \tilde{H}$ the closure of ...
2
votes
0answers
305 views

Is there an infinite J-group?

For a group $G$ let $\operatorname{Sub}(G)$ be the lattice of all its subgroups. A subgroup interval is an interval in the lattice $\operatorname{Sub}(G)$. A group $G$ is called a J-group iff ...
4
votes
1answer
166 views

Automorphisms of SO_n(k,f)

Let $k$ be a field, $n\in\mathbb{N}$ and $f:k^n\times k^n\to k$ a non-degenerate symmetric bilinear form. Let $$O_n(k,f):=\{ g\in GL_n(k) \mid \forall x,y\in k^n : f(x,y)=f(g.x,g.y) \}$$ and ...
4
votes
0answers
203 views

Polynomial dynamical systems

The question is somewhat related to the theory of permutation polynomials. Let $\mathbb{F}_p$ be a finite field of $p$ elements ($p$ is prime) and $\mathcal{V} = \mathbb{F}_p^2 = \{ (t_1,t_2)\::\: ...
11
votes
2answers
518 views

Multiplicative Identity for all elements in SU(n)

Let $\{P_i\}$ be a subset of $SU(n)$ such that for any $U$ in another subset (or perhaps subgroup) $H$ of $SU(n)$: $$P_1UP_2U\cdots P_mU=I$$ where $I$ is the identity element. Is there a sequence ...
2
votes
1answer
108 views

Existence of an infinite finitely generated $p$-group with nontrivial intersection of nontrivial subgroups

Is there an infinite finitely generated (non-cyclic) $p$-group $G$ such that the intersection of all nontrivial subgroups of $G$ is a nontrivial subgroup?
5
votes
1answer
159 views

Properties of the Burnside kernel

Let $p$ be a prime such that the free 2-generator group $B(2,p)$ of exponent $p$ is infinite. Consider the short exact sequence $$ 1\to K \to B(2,p) \to B_0(2,p) \to 1, $$ where $B_0(2,p)$ is the ...
1
vote
1answer
131 views

Maximal compact subgroups of a semisimple Lie group are conjugate

I'm trying to go through the proof that all maximal compact subgroups of a semisimple Lie group $G$ are conjugate. I know that a possible proof follows the following steps: Take one maximal compact ...
0
votes
3answers
162 views

quasiprimitive non-solvable groups

I'm looking for the reference about quasiprimitive unsoluble groups. Actually we can find a lot of useful things about quasiprimitive solvable groups in "Representations of solvable groups by Manz and ...
9
votes
1answer
285 views

Factorization of a finite group by two subsets

I want to write a GAP program for checking the following question. Let $G$ be a given finite group with order $n$. Is it true that for every factorization $n=ab$ there exist subsets $A$ and $B$ ...
2
votes
1answer
163 views

Does the set of automorphisms of a cyclic group exhibit some sense of randomness?

I prefer to proceed with a concrete example if I may. I appreciate that the answer might well be better explained with group theory, geometry and/or notions from probability theory, which I welcome. ...
2
votes
1answer
76 views

Double quotients of Coxeter groups have the chain property?

Let $(W,S)$ be a Coxeter group with Bruhat order $\leq$ and length function $\ell(w)$. Definition: a subset $X \subset W$ has the chain property if whenever $x,y \in X$ with $x < y$, there ...
0
votes
0answers
78 views

Bases and transversals

Let $F$ be a free finitely generated group, $L \leq H \leq F$ subgroups of finite index. Given bases $B$ of $F$ and $C$ of $H$, must there be a Schreier transversal $T$ for $H$ in $F$ such that the ...
2
votes
1answer
104 views

Isolated elements of primary order ($Z^*$-theorem revisited)

Let $G$ be a finite group, $p$ a prime, $P\in{\rm Syl}_p(G)$, and $x\in P$. Let $Z^*_p(G)$ denote the full preimage in $G$ of $Z(G/O_{p'}(G))$ under the canonical epimorphism $G\to G/O_{p'}(G)$. ...
2
votes
2answers
170 views

Bound on the index of an abelian subgroup in discrete subgroup of the euclidean group?

I asked the following question on math.SE a couple of days ago. Dietrich Burde gave an answer for the case that the subgroup is not only discrete but also acts cocompactly. What about the general ...
3
votes
1answer
234 views

Generating finite groups

Let $G$ be a finite group possessing a generating set of order $n \in \mathbb{N}$. Let $H \leq G$ and $x_1, \dots, x_n \in G$ for which $\langle H, x_1, \dots, x_n \rangle = G$. Must there be $h_1, ...