scholarly journals The CI Problem for Infinite Groups

10.37236/5056 ◽  
2016 ◽  
Vol 23 (4) ◽  
Author(s):  
Joy Morris
Keyword(s):  
Finite Group ◽  
Cayley Graphs ◽  
Torsion Group ◽  
Infinite Group ◽  
Infinite Groups ◽  
Open Problems ◽  
Locally Finite ◽  
A Finite Group

A finite group $G$ is a DCI-group if, whenever $S$ and $S'$ are subsets of $G$ with the Cayley graphs Cay$(G,S)$ and Cay$(G,S')$ isomorphic, there exists an automorphism $\varphi$ of $G$ with $\varphi(S)=S'$. It is a CI-group if this condition holds under the restricted assumption that $S=S^{-1}$. We extend these definitions to infinite groups, and make two closely-related definitions: an infinite group is a strongly (D)CI$_f$-group if the same condition holds under the restricted assumption that $S$ is finite; and an infinite group is a (D)CI$_f$-group if the same condition holds whenever $S$ is both finite and generates $G$.We prove that an infinite (D)CI-group must be a torsion group that is not locally-finite. We find infinite families of groups that are (D)CI$_f$-groups but not strongly (D)CI$_f$-groups, and that are strongly (D)CI$_f$-groups but not (D)CI-groups. We discuss which of these properties are inherited by subgroups. Finally, we completely characterise the locally-finite DCI-graphs on $\mathbb Z^n$. We suggest several open problems related to these ideas, including the question of whether or not any infinite (D)CI-group exists.

Locally Finite Products of Totally Permutable Nilpotent Groups

2009 ◽  
Vol 16 (03) ◽  
pp. 535-540 ◽  
Author(s):  
Maria De Falco ◽  
Francesco de Giovanni ◽  
Carmela Musella
Keyword(s):  
Finite Group ◽  
Nilpotent Groups ◽  
Infinite Groups ◽  
Locally Finite ◽  
Finite Products ◽  
A Finite Group

A group G=AB is said to be totally factorized by its subgroups A and B if XY=YX for all subgroups X of A and Y of B. It is known that any finite group totally factorized by supersoluble subgroups is supersoluble, and that a finite group totally factorized by nilpotent subgroups is abelian-by-nilpotent. This latter result is extended here to certain classes of infinite groups.

scholarly journals Growth in Infinite Groups of Infinite Subsets

2015 ◽  
Vol 22 (02) ◽  
pp. 333-348
Author(s):  
J. O. Button
Keyword(s):  
Finite Group ◽  
Invariant Measure ◽  
Finite Index ◽  
Infinite Group ◽  
Infinite Groups ◽  
A Finite Group ◽  
Finite Index Subgroups ◽  
Free Sets

Given an infinite group G, we consider the finitely additive invariant measure defined on finite unions of cosets of finite index subgroups. We show that this shares many properties with the size of subsets of a finite group, for instance we can obtain equivalent results on the Ruzsa distance and product free sets. In particular, if G has infinitely many finite index subgroups, then it has subsets S of measure arbitrarily close to 1/2 with square S2 having measure less than 1. We also examine properties of the Ruzsa distance on the set of finite index subgroups of an infinite group, whereupon it becomes a genuine metric.

scholarly journals On the generic family of Cayley graphs of a finite group

2021 ◽  
Vol 184 ◽  
pp. 105495
Author(s):  
Czesław Bagiński ◽  
Piotr Grzeszczuk
Keyword(s):  
Finite Group ◽  
Cayley Graphs ◽  
A Finite Group ◽  
Generic Family

scholarly journals Integral Cayley Graphs over Abelian Groups

10.37236/353 ◽  
2010 ◽  
Vol 17 (1) ◽  
Author(s):  
Walter Klotz ◽  
Torsten Sander
Keyword(s):  
Finite Group ◽  
Abelian Group ◽  
Boolean Algebra ◽  
Cayley Graph ◽  
Cayley Graphs ◽  
Additive Group ◽  
Cyclic Groups ◽  
Vertex Set ◽  
A Finite Group ◽  
Gamma S

Let $\Gamma$ be a finite, additive group, $S \subseteq \Gamma, 0\notin S, -S=\{-s: s\in S\}=S$. The undirected Cayley graph Cay$(\Gamma,S)$ has vertex set $\Gamma$ and edge set $\{\{a,b\}: a,b\in \Gamma$, $a-b \in S\}$. A graph is called integral, if all of its eigenvalues are integers. For an abelian group $\Gamma$ we show that Cay$(\Gamma,S)$ is integral, if $S$ belongs to the Boolean algebra $B(\Gamma)$ generated by the subgroups of $\Gamma$. The converse is proven for cyclic groups. A finite group $\Gamma$ is called Cayley integral, if every undirected Cayley graph over $\Gamma$ is integral. We determine all abelian Cayley integral groups.

scholarly journals Finite automorphism groups of laminated near-rings

1983 ◽  
Vol 26 (3) ◽  
pp. 297-306 ◽  
Author(s):  
K. D. Magill ◽  
P. R. Misra ◽  
U. B. Tewari
Keyword(s):  
Finite Group ◽  
Linear Group ◽  
Complex Plane ◽  
Finite Groups ◽  
Automorphism Groups ◽  
The Other ◽  
Complex Polynomial ◽  
Infinite Groups ◽  
Nonsingular Matrices ◽  
A Finite Group

In [3] we initiated our study of the automorphism groups of a certain class of near-rings. Specifically, let P be any complex polynomial and let P denote the near-ring of all continuous selfmaps of the complex plane where addition of functions is pointwise and the product fg of two functions f and g in P is defined by fg=f∘P∘g. The near-ring P is referred to as a laminated near-ring with laminating element P. In [3], we characterised those polynomials P(z)=anzn + an−1zn−1 +…+a0 for which Aut P is a finite group. We are able to show that Aut P is finite if and only if Deg P≧3 and ai ≠ 0 for some i ≠ 0, n. In addition, we were able to completely determine those infinite groups which occur as automorphism groups of the near-rings P. There are exactly three of them. One is GL(2) the full linear group of all real 2×2 nonsingular matrices and the other two are subgroups of GL(2). In this paper, we begin our study of the finite automorphism groups of the near-rings P. We get a result which, in contrast to the situation for the infinite automorphism groups, shows that infinitely many finite groups occur as automorphism groups of the near-rings under consideration. In addition to this and other results, we completely determine Aut P when the coefficients of P are real and Deg P = 3 or 4.

scholarly journals Conjugate purity and infinite groups

1979 ◽  
Vol 28 (1) ◽  
pp. 9-14
Author(s):  
Bola O. Balogun
Keyword(s):  
Finite Group ◽  
Subject Classification ◽  
Infinite Groups ◽  
Soluble Groups ◽  
Infinite Case ◽  
A Finite Group

AbstractIn Balogun (1974), we proved that a finite group in which every subgroup is conjugately pure is necessarily Abelian and we left open the infinite case. In this paper we settle this problem positively for soluble, locally soluble groups and certain classes of groups which include the FC-groups. In the last section of this paper we characterize groups which are conjugately pure in every containing group.Subject classification (Amer. Math. Soc. (MOS) 1970): 20 E 99.

On locally nilpotent groups

1956 ◽  
Vol 52 (1) ◽  
pp. 5-11 ◽  
Author(s):  
D. H. McLain ◽  
P. Hall
Keyword(s):  
Finite Group ◽  
Nilpotent Group ◽  
Direct Product ◽  
Finite Subset ◽  
Nilpotent Groups ◽  
Finitely Generated ◽  
Locally Finite ◽  
Locally Nilpotent Groups ◽  
Locally Nilpotent ◽  
A Finite Group

1. If P is any property of groups, then we say that a group G is ‘locally P’ if every finitely generated subgroup of G satisfies P. In this paper we shall be chiefly concerned with the case when P is the property of being nilpotent, and will examine some properties of nilpotent groups which also hold for locally nilpotent groups. Examples of locally nilpotent groups are the locally finite p-groups (groups such that every finite subset is contained in a finite group of order a power of the prime p); indeed, every periodic locally nilpotent group is the direct product of locally finite p-groups.

scholarly journals Two bounds on the noncommuting graph

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Stefano Nardulli ◽  
Francesco G. Russo
Keyword(s):  
Finite Group ◽  
General Context ◽  
Sobolev Inequalities ◽  
Classical Analysis ◽  
Locally Finite ◽  
Finite Graphs ◽  
Locally Finite Graphs ◽  
A Finite Group ◽  
Noncommuting Graph ◽  
First Time

AbstractErdős introduced the noncommuting graph in order to study the number of commuting elements in a finite group. Despite the use of combinatorial ideas, his methods involved several techniques of classical analysis. The interest for this graph has become relevant during the last years for various reasons. Here we deal with a numerical aspect, showing for the first time an isoperimetric inequality and an analytic condition in terms of Sobolev inequalities. This last result holds in the more general context of weighted locally finite graphs.

scholarly journals On automorphisms of graded quasi-lie algebras

Filomat ◽  
2020 ◽  
Vol 34 (9) ◽  
pp. 3141-3150
Author(s):  
Dae-Woong Lee ◽  
Sunyoung Lee ◽  
Yeonjeong Kim ◽  
Jeong-Eun Lim
Keyword(s):  
Finite Group ◽  
Lie Algebras ◽  
Infinite Group ◽  
Ring Of Integers ◽  
A Finite Group

Let Z be the ring of integers and let K(Z,2n) denote the Eilenberg-MacLane space of type (Z,2n) for n ? 1. In this article, we prove that the graded group Am := Aut(??2mn+1(?K(Z,2n))=torsions) of automorphisms of the graded quasi-Lie algebras ?? 2mn+1(?K(Z,2n)) modulo torsions that preserve the Whitehead products is a finite group for m ? 2 and an infinite group for m ? 3, and that the group Aut(?*(K(Z,2n))=torsions) is non-abelian. We extend and apply those results to techniques in localization (or rationalization) theory.

Integral Cayley Graphs over Finite Groups

2020 ◽  
Vol 27 (01) ◽  
pp. 131-136
Author(s):  
Elena V. Konstantinova ◽  
Daria Lytkina
Keyword(s):  
Finite Group ◽  
Symmetric Group ◽  
Cayley Graph ◽  
Cyclic Group ◽  
Finite Groups ◽  
Cayley Graphs ◽  
Alternating Group ◽  
Generating Set ◽  
A Finite Group

We prove that the spectrum of a Cayley graph over a finite group with a normal generating set S containing with every its element s all generators of the cyclic group 〈s〉 is integral. In particular, a Cayley graph of a 2-group generated by a normal set of involutions is integral. We prove that a Cayley graph over the symmetric group of degree n no less than 2 generated by all transpositions is integral. We find the spectrum of a Cayley graph over the alternating group of degree n no less than 4 with a generating set of 3-cycles of the form (k i j) with fixed k, as {−n+1, 1−n+1, 22 −n+1, …, (n−1)2 −n+1}.

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