Questions tagged [p-groups]
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137
questions
33
votes
2
answers
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Richness of the subgroup structure of p-groups
Given a prime $p$ and $n \in \mathbb{N}$, let $f_p(n)$ be the smallest
number such that there is a group of order $p^{f_p(n)}$ which all groups of
order $p^n$ embed into. What is the asymptotic growth ...
- 19.3k
32
votes
3
answers
3k
views
Is there a nice explanation for this curious fact about cyclic subgroups?
Here's something that I noticed that quite surprised me.
Let $G$ be a finite abelian group. Consider the following expression.
$$
\nu(G) = \sum_{\substack{H \leq G \\ H \text{ is cyclic}}} |H|
$$
It ...
- 6,242
21
votes
0
answers
562
views
p-groups as rational points of unipotent groups
Is it true that every finite p-group can be realized as the group of rational points over $\mathbb{F_p}$ of some connected unipotent algebraic group defined over $\mathbb{F_p}$? For abelian p-groups, ...
- 221
19
votes
1
answer
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views
Groups with a unique lonely element
Does there exist a finite group $G$ of order greater than two containing a unique element $g$ such that
$$
g\notin\langle x\rangle
\hbox{ for all $x\in G\setminus\{g\}$ ?}
$$
Or we have another ...
- 3,902
13
votes
1
answer
434
views
Variety of nilpotent Lie algebras or $p$-groups
Here's a couple of analogous questions, one in terms of finite-dimensional complex Lie algebras and one in terms of finite $p$-groups; I'd be interested in an answer to either:
1) Let $\mathcal{L}$ ...
- 59.4k
11
votes
1
answer
478
views
Is the norm element characteristic in modular group rings?
Let $G$ be a finite $p$- group and let $\varphi$ be an automorphism of $\mathbb{F}_pG$ as $\mathbb{F}_p$-algebras and let $n = \sum_{g\in G} g$ be the norm element. Does it follow that $\varphi(n)=n$?
...
- 10.1k
10
votes
3
answers
936
views
faithful unipotent representations of (finite) $p$-groups
The title pretty much summarizes the question: does every $p$-group have a faithful unipotent representation (with coefficients in $\mathbb{F}_p$ or some finite extension thereof)?
- 95.3k
10
votes
5
answers
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views
Automorphism Group of a p-group : Looking for a Reference
In the following post by DavidLHarden :
See Here
He quoted the following claim:
"There is a theorem that says that if $p$ is a prime and $|G|=p^n $ , then $|AutG| $ divides
$ \Pi_{k=0}^{n-1} (p^{n}-...
- 253
10
votes
3
answers
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views
Number of Normal subgroups In a p-Group
Dear all,
Does someone know of any paper/method that enables us counting/estimating the number of normal subgroups of some p-group of order $p ^n $ ($ n$ is some natural number ? ) .
Is there anyway ...
- 253
10
votes
4
answers
1k
views
Classification of automorphism groups of groups of order $p^4$
For the purpose of classifying another algebraic structure which is parametrised by the choice of a group and of an automorphism I need the classification up to isomorphism of automorphism groups of p-...
- 744
10
votes
1
answer
569
views
Maximal subgroups of a certain finite 2-group
The following came up in a problem on reconstruction of digraphs. I determined enough about the answer to satisfy the application completely, but still I am curious to know what the complete solution ...
- 37k
9
votes
2
answers
373
views
Which finite p-groups occur as commutators of finite p-groups?
Let $p$ be a prime number. For which finite $p$-groups $H$ is there a finite $p$-group $G$ such that $[G,G] \cong H$?
- 11.2k
9
votes
1
answer
281
views
p-groups such that the center is contained in many cyclic subgroups
I'm looking for examples of $p$-groups $G$ with the following three properties:
the center of $G$ is $\mathbb{Z}/p$, and
$G^{\text{ab}} = (\mathbb{Z}/p)^n$ for some $n$, and
for every $g \in G$ whose ...
- 91
8
votes
8
answers
4k
views
classification of $p$-groups
I have two questions regarding to $p$-groups.
A $p$-group $G$ is said to be extraspecial of $G'=Z(G)$ has order $p$. Hence extraspecial groups are examples of $p$-groups with cyclic center. Of ...
- 2,458
8
votes
2
answers
456
views
Uniform-in-p classification* of p-groups of order p^n for each fixed n?
To what extent is there/can there be a description that is uniform in p (for p sufficiently large) of the p-groups of order $p^n$, for each fixed n?
Note 1: I used the word "description" rather than ...
- 2,817
8
votes
2
answers
1k
views
Representation theory of a finite p-group over a field of characteristic p: dim of invariants =1 => dim of coinvariants = 1?
I am trying to understand the proof of Proposition 4 in
S. Ullom, Integral normal bases in Galois extensions of local fields, Nagoya Math. J. Volume 39 (1970), 141-148. The PDF is available here:
http:...
- 1,631
8
votes
2
answers
294
views
Is the free abstract group residually of rank d > 2?
Let $d \geq 2$ be an integer, and let $\mathcal{F}_d$ be the family of finite groups such that $G \in \mathcal{F}_d$ if and only if every subgroup of $G$ can be generated by at most $d$ elements.
Is ...
- 11.2k
8
votes
1
answer
520
views
Constructing a group of order $2187=3^7$
I am trying to look for the $2$-generated groups of order $3^7$ and class $4$ all whose upper central series quotients are elementary abelian of order 9 except the center which has order $3$.
A small ...
- 405
7
votes
3
answers
873
views
Characters of p-groups
Berkovich mentioned the following result of Mann in his book on p-groups:
The number of nonlinear irreducible characters of given degree in a p-group is divided by p-1.
Do you know any reference for ...
- 307
7
votes
3
answers
611
views
p-group with large center
Is there any characterization for $p$-groups of order greater than $p^3$ which center has index $p^2$? (One group whit this property if $M(p^n)$)
- 139
7
votes
1
answer
364
views
Is $[729,57]$ a Sylow $3$-subgroup of some well-known group?
Let $G$ be the group $[729,57]$, using GAP's notation. I have so far two descriptions of the group:
a presentation
an embedding (not surjective!) of the group into a Sylow $3$-subgroup of the unit ...
user76083
6
votes
3
answers
892
views
Union of conjugates of a subgroup
Let $G$ be a finite group, $H \leq G$ a proper subgroup. It is well known that the union of the conjugates of $H$ does not cover $G$. I would like to know of more precise results (even in special ...
- 11.2k
6
votes
1
answer
156
views
Is the largest normal abelian subgroup of a finite 2-group $P$ of order at least the square root of the order of $P$?
Let $G$ be a group of order $2^n$. Does $G$ have a normal abelian subgroup of order at least $2^{n/2}$?
(This is true, via computations in GAP, for $n \le 8$.
The question is similar to one posed ...
- 931
6
votes
1
answer
203
views
Is there a subgroup of a non-abelian $p$-group $G$ with a large nilpotency class?
Let $G$ be a non-abelian $p$-group ($p\ne2$). Does there exist a group $H\subset G$ such that both 1, 2 are satisfied?
$|H| = |G|/p$.
$c(H)\geq c(G) - 1$.
- 291
6
votes
2
answers
291
views
Differences between $p$-groups and $q$-groups
First, let me include the same disclaimer that goes in the first line of any article I write: all groups considered herein are finite.
Academically, I work with connecting the arithmetic structure of ...
6
votes
1
answer
291
views
Maximal cyclic quotient of a $p$-group
Let $G$ be a finite abelian $p$-group, $p$ a prime. I say that a pair $(G',\varphi)$ is a maximal cyclic quotient (please excuse me if this definition already exists and refers to a different concept) ...
- 509
6
votes
1
answer
362
views
Finite 2-groups with $(ab)^{2}=(ba)^{2}$
There exist nonabelian finite 2-groups $G$ with the property $(A2)$ : for every $a,b\in G$, $(ab)^{2}=(ba)^{2}$. An example of a such group is given by the quaternion group $Q_{8}$ of order 8. Is ...
- 933
6
votes
1
answer
485
views
On classifying groups of order $p^5$
Can someone suggest me some source where the author has classified all non-isomorphic groups of order $p^5$ ? I need complete classification (not upto isoclinism), and also in finitely presented form ....
- 381
6
votes
1
answer
136
views
$p$-groups with isomorphic subgroup lattices
Given two non-abelian finite p-groups $P_1$ and $P_2$ of the same order that are not isomorphic.
Can $P_1$ and $P_2$ have isomorphic subgroup lattices?
(I'm not experienced with group theory, ...
- 25.4k
6
votes
2
answers
178
views
Agemo-of-agemo inclusions for p-groups
For a finite $p$-group $G$, let $\mho_i(G)$ denote the subgroup generated by $p^i$-powers of elements of $G$.
It is well-known that $\mho_i(\mho_j(G))$ can differ from $\mho_j(\mho_i(G))$ and from $\...
- 2,469
6
votes
1
answer
814
views
Extra special p-groups
Let $P$ be an infinite extra special $p$-group for some prime $p$, namely, $Z(P)=P'=\Phi(P)$ and $P/Z(P)$ is infinite elementary abelian.
Let $C$ be a Prufer $q$-group for some prime $q\neq p$.
...
- 137
6
votes
1
answer
657
views
Torsion in profinite groups
Is there a finitely generated profinite group $G$ with a closed subgroup of infinite index $K \leq G$ such that for every $g \in G$ there exists some $n \in \mathbb{N}$ for which $g^n \in K$ ?
Can $G$...
- 11.2k
6
votes
0
answers
103
views
Random pro-p groups via iterated uniformly random central extensions
Inspired by this question on math.se, I want to understand the following construction of a random pro-$p$ group:
We want to construct an inverse system
$$\cdots \xrightarrow{\alpha_i} G_i \...
- 381
6
votes
0
answers
192
views
Is there a Noetherian profinite group of infinite rank?
Is there a profinite group $G$ such that any closed subgroup $H \leq G$ is finitely generated, but there is no $n \in \mathbb{N}$ such that every closed subgroup of $G$ can be generated by at most $n$ ...
- 11.2k
6
votes
0
answers
406
views
An example of a simple infinite 2-group
I've asked this question before on Mathematics, and they suggested me to ask here (Link).
Is there an example of a simple infinite $2$-group?
Informations
If a $2$-group is Artinian I know that it ...
- 599
5
votes
3
answers
535
views
Normal abelian subgroups in p-groups
Given a group $G$, we denote by $T(G)$ the subgroup generated by all (maximal) normal abelian subgroups of $G$.
Let define the series $(T_i(G))$ by $T_0(G)=1$ and $T_{i+1}(G)/T_i(G)=T(G/T_i(G)$, and $...
5
votes
1
answer
152
views
Do these $p$-groups have the same nilpotency class?
Let $G$ be a $p$-group, $\{e\}\not= H\subseteq G$ be a subgroup of $G$ such that $G' = H'$. Is it true that $c(G) = c(H)$, where $c(\cdot)$ denotes the nilpotency class of a group?
- 291
5
votes
1
answer
233
views
Number of subgroups of a $p$-group of index $p^k$
Let $p$ be a prime, let $n$ and $k$ be positive integers
and let $G$ be a group of order $p^n$.
Further, let $a_{p^k}$ denote the number of subgroups of $G$ of index $p^k$.
If $a_{p^k}$ is greater ...
- 347
5
votes
1
answer
218
views
Finite solvable groups are generated by a nilpotent subgroup + K elements?
Is there a constant $K \in \mathbb{N}$ such that for every finite solvable group $G$, there exists a nilpotent subgroup $N \leq G$, and a subset $S \subseteq G$ with $|S| \leq K$, and $\langle N,S\...
- 11.2k
5
votes
3
answers
370
views
Hall algebra for non-abelian $p$-groups?
According to WP article on Hall algebras one counts the number of abelian subgroups in an abelian group with fixed type of subgroup, group, quotient.
Two things are claimed:
These numbers are ...
- 22.9k
5
votes
2
answers
734
views
Center of finite metabelian p-groups
$\DeclareMathOperator\rk{rk}$
Let $G$ be a finite metabelian $p$-group, i.e. the commutator subgroup $G'$ of $G$ is abelian. Then I ask myself under which conditions does the following hold:
$$\tag{$*...
5
votes
1
answer
199
views
Local vs global nilpotence class (Lazard correspondence)
The Lazard Correspondence is often phrased (for simplicity) for $p$-groups of nilpotence class $c < p$, but it works more generally whenever every 3-generated subgroup has nilpotence class $< p$,...
- 2,817
5
votes
0
answers
183
views
Can an infinite abelian $p$-group be tall and thin?
Does there exist an abelian $p$-group $A$ with countable Ulm invariants and uncountable height?
Here by height, I mean the minimal ordinal $\rho$ such that $p^\rho A$ is divisible [1]. For an ordinal ...
- 59k
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votes
0
answers
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views
How can I get my hands on McKay's "Finite p-Groups" lecture notes?
The notes I'm talking about are these.
I emailed Peter Cameron, but he has since moved to a different university, and has no copies himself. I also emailed the school manager at Queen Mary, but they ...
- 4,327
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votes
0
answers
293
views
A class 3 group of order 243
Let G be a group of order $243=3^5$. We denote by $(G_i)$ its lower central series and assume that $G$ has class $3$ and that $|G:G_2|=|G_3|=9$. We assume moreover that the cubing map factors as a (...
user76083
4
votes
4
answers
3k
views
Center of p-groups
Can one show that any abelian $p$-group (not necessarily finite) is the center of a $p$-group and of index $p$?
4
votes
3
answers
2k
views
Representation theory of p-groups in particular upper tringular matrices over F_p
Finite p-groups - have p^n elements by definition. According to WP there is rich structure theory.
Question: How far is representation theory of p-groups is understood?
In case this question is too ...
- 22.9k
4
votes
3
answers
484
views
Molien for modular representations?
Let $G$ be a finite group, and let $k$ be a field whose characteristic divides $\left|G\right|$. Let $\rho:G\to \mathrm{End} V$ be a (finite-dimensional) representation of $G$ over $k$. Prove or ...
- 32.7k
4
votes
1
answer
195
views
Finite p-groups and their fibered products
Is every finite $p$-group an epimorphic image of a fibered product of two finite $p$-groups which can be generated by $2$ elements?
- 11.2k
4
votes
1
answer
418
views
Generators of p-groups
Let $G$ be a finite $p$-group. Since we can embed $Z_2(G)/Z(G)$ in $Hom(G,Z(G))$, we have $d_2 \leq d(G)d(Z(G))$; where $d_2(G)=d(Z_2(G)/Z(G))$ and $d(G)$ denotes the minimal number of generators of $...