Profinite Modules

1973 ◽  
Vol 16 (3) ◽  
pp. 405-415
Author(s):  
Gerard Elie Cohen
Keyword(s):  
Finite Group ◽  
General Theory ◽  
Finite Length ◽  
Finite Groups ◽  
Inverse Limit ◽  
Abelian Groups ◽  
Point Of View ◽  
Inverse Limits ◽  
Profinite Groups ◽  
Inverse Systems

An inverse limit of finite groups has been called in the literature a pro-finite group and we have extensive studies of profinite groups from the cohomological point of view by J. P. Serre. The general theory of non-abelian modules has not yet been developed and therefore we consider a generalization of profinite abelian groups. We study inverse systems of discrete finite length R-modules. Profinite modules are inverse limits of discrete finite length R-modules with the inverse limit topology.

scholarly journals Impartial achievement games for generating nilpotent groups

2019 ◽  
Vol 22 (3) ◽  
pp. 515-527
Author(s):  
Bret J. Benesh ◽  
Dana C. Ernst ◽  
Nándor Sieben
Keyword(s):  
Finite Group ◽  
Finite Groups ◽  
Abelian Groups ◽  
Nilpotent Groups ◽  
Generating Set ◽  
Odd Order ◽  
Impartial Game ◽  
A Finite Group

AbstractWe study an impartial game introduced by Anderson and Harary. The game is played by two players who alternately choose previously-unselected elements of a finite group. The first player who builds a generating set from the jointly-selected elements wins. We determine the nim-numbers of this game for finite groups of the form{T\times H}, whereTis a 2-group andHis a group of odd order. This includes all nilpotent and hence abelian groups.

A Note on Inverse Limits of Finite Spaces

1970 ◽  
Vol 13 (1) ◽  
pp. 69-70
Author(s):  
S. B. Nadler
Keyword(s):  
Finite Groups ◽  
Inverse Limit ◽  
Inverse System ◽  
Inverse Limits ◽  
Hausdorff Spaces ◽  
Finite Spaces

The following lemma, which appears as Lemma 4 in [5], was used to determine certain multicoherence properties of inverse limits of continua.Lemma. Let X denote the inverse limit of an inverse system {Xλ, fλμ, Λ} of compact Hausdorff spaces Xλ. If Xλ has no more than k components (where k < ∞ is fixed) for each λ ∊ Λ, then X has no more than k components.In this paper we give a set theoretic analogue of this lemma and an extension which was suggested to the author by Professor F. W. Lawvere. An application to inverse limits of finite groups is then given.

Effective aspects of profinite groups

1981 ◽  
Vol 46 (4) ◽  
pp. 851-863 ◽  
Author(s):  
Rick L. Smith
Keyword(s):  
Finite Groups ◽  
Inverse Limit ◽  
Commutator Subgroup ◽  
Galois Groups ◽  
Profinite Group ◽  
Profinite Groups ◽  
Frattini Subgroup ◽  
A Finite Group ◽  
Work Done ◽  
General Method

Profinite groups are Galois groups. The effective study of infinite Galois groups was initiated by Metakides and Nerode [8] and further developed by LaRoche [5]. In this paper we study profinite groups without considering Galois extensions of fields. The Artin method of representing a finite group as a Galois group has been generalized (effectively!) by Waterhouse [14] to profinite groups. Thus, there is no loss of relevance in our approach.The fundamental notions of a co-r.e. profinite group, recursively profinite group, and the degree of a co-r.e. profinite group are defined in §1. In this section we prove that every co-r.e. profinite group can be effectively represented as an inverse limit of finite groups. The degree invariant is shown to behave very well with respect to open subgroups and quotients. The work done in this section is basic to the rest of the paper.The commutator subgroup, the Frattini subgroup, thep-Sylow subgroups, and the center of a profinite group are essential in the study of profinite groups. It is only natural to ask if these subgroups are effective. The following question exemplifies our approach to this problem: Is the center a co-r.e. profinite group? Theorem 2 provides a general method for answering this type of question negatively. Examples 3,4 and 5 are all applications of this theorem.

scholarly journals COMMUTATIVITY DEGREE OF A CLASS OF FINITE GROUPS AND CONSEQUENCES

2013 ◽  
Vol 88 (3) ◽  
pp. 448-452 ◽  
Author(s):  
RAJAT KANTI NATH
Keyword(s):  
Finite Group ◽  
Semidirect Product ◽  
Finite Groups ◽  
Abelian Groups ◽  
Affirmative Answer ◽  
Finite Abelian Groups ◽  
A Finite Group ◽  
Open Question

AbstractThe commutativity degree of a finite group is the probability that two randomly chosen group elements commute. The object of this paper is to compute the commutativity degree of a class of finite groups obtained by semidirect product of two finite abelian groups. As a byproduct of our result, we provide an affirmative answer to an open question posed by Lescot.

Topological Properties of Limits of Inverse Systems Of Measures

1974 ◽  
Vol 26 (6) ◽  
pp. 1455-1465 ◽  
Author(s):  
Donald J. Mallory
Keyword(s):  
Inverse Limit ◽  
Product Space ◽  
Point Of View ◽  
Limit Set ◽  
Topological Properties ◽  
Limit Measure ◽  
Radon Measures ◽  
Inverse Systems ◽  
Similar Point ◽  
Measure Spaces

It has been shown (Mallory and Sion [6]) that the problem of finding "limit" measures for inverse systems of measure spaces (Xi, μi)i∊I can be successfully attacked by establishing the existence of a “limit” measure on the product space , then considering the restriction to the inverse limit set .In this paper we use a similar point of view to establish conditions under which a system of Radón measures has a “limit” measure which is also Radón.

scholarly journals Some topological properties of residually Černikov groups

1982 ◽  
Vol 23 (1) ◽  
pp. 65-82 ◽  
Author(s):  
M. R. Dixon
Keyword(s):  
Finite Groups ◽  
Inverse Limit ◽  
Normal Subgroups ◽  
Topological Properties ◽  
Profinite Groups ◽  
Dense Subgroup ◽  
Locally Finite ◽  
Soluble Groups ◽  
Residually Finite ◽  
Residually Finite Group

In this paper we shall indicate how to generalise the concept of a cofinite group (see [7]). We recall that any residually finite group can be made into a topological group by taking as a basis of neighbourhoods of the identity precisely the normal subgroups of finite index. The class of compact cofinite groups is then easily seen to be the class of profinite groups, where a group is profinite if and only if it is an inverse limit of finite groups. It turns out that every cofinite group can be embedded as a dense subgroup of a profinite group. This has important consequences for the class of countable locally finite-soluble groups with finite Sylow p-subgroups for all primes p, as shown in [7] and [14].

Cokernels of Homomorphisms from Burnside Rings to Inverse Limits

2017 ◽  
Vol 60 (1) ◽  
pp. 165-172 ◽  
Author(s):  
Masaharu Morimoto
Keyword(s):  
Finite Group ◽  
Normal Subgroup ◽  
Inverse Limit ◽  
Minimal Normal Subgroup ◽  
Cartesian Product ◽  
Inverse Limits ◽  
Burnside Ring ◽  
A Finite Group ◽  
Burnside Rings ◽  
Natural Way

AbstractLet G be a finite group and let A(G) denote the Burnside ring of G. Then an inverse limit L(G) of the groups A(H) for proper subgroups H of G and a homomorphism res from A(G) to L(G) are obtained in a natural way. Let Q(G) denote the cokernel of res. For a prime p, let N(p) be the minimal normal subgroup of G such that the order of G/N(p) is a power of p, possibly 1. In this paper we prove that Q(G) is isomorphic to the cartesian product of the groups Q(G/N(p)), where p ranges over the primes dividing the order of G.

scholarly journals The geometry and fundamental groups of solenoid complements

2015 ◽  
Vol 24 (14) ◽  
pp. 1550069 ◽  
Author(s):  
Gregory R. Conner ◽  
Mark Meilstrup ◽  
Dušan Repovš
Keyword(s):  
Fundamental Group ◽  
Inverse Limit ◽  
Abelian Groups ◽  
Inverse Limits ◽  
Fundamental Groups ◽  
Three Space

A solenoid is an inverse limit of circles. When a solenoid is embedded in three space, its complement is an open three manifold. We discuss the geometry and fundamental groups of such manifolds, and show that the complements of different solenoids (arising from different inverse limits) have different fundamental groups. Embeddings of the same solenoid can give different groups; in particular, the nicest embeddings are unknotted at each level, and give an Abelian fundamental group, while other embeddings have non-Abelian groups. We show using geometry that every solenoid has uncountably many embeddings with nonhomeomorphic complements.

On the probability that an automorphism of a group fixes an element of the group

2019 ◽  
Vol 19 (10) ◽  
pp. 2050198
Author(s):  
Ashish Goyal ◽  
Hemant Kalra ◽  
Deepak Gumber
Keyword(s):  
Finite Group ◽  
Maximal Subgroup ◽  
Finite Groups ◽  
Abelian Groups ◽  
Finite Abelian Groups ◽  
A Finite Group

Let [Formula: see text] be a finite group and let [Formula: see text] denote the probability that a randomly chosen element from [Formula: see text] fixes a randomly chosen element from [Formula: see text]. We classify all finite abelian groups [Formula: see text] such that [Formula: see text] in the cases when [Formula: see text] is the smallest prime dividing [Formula: see text], and when [Formula: see text] is any prime. We also compute [Formula: see text] for some classes of finite groups. As a consequence of our results, we deduce that if [Formula: see text] is a finite [Formula: see text]-group having a cyclic maximal subgroup, then [Formula: see text] divides [Formula: see text].

Prosolvability criteria and properties of the prosolvable radical via Sylow sequences

2016 ◽  
Vol 19 (3) ◽  
Author(s):  
Wolfgang Herfort ◽  
Dan Levy
Keyword(s):  
Finite Group ◽  
Finite Groups ◽  
Simple Groups ◽  
Profinite Groups ◽  
Sylow Subgroups ◽  
Solvability Criterion ◽  
A Finite Group

AbstractWe extend a finite group solvability criterion of J. G. Thompson, based on his classification of finite minimal simple groups, to a prosolvability criterion. Moreover, we generalize to the profinite setting subsequent developments of Thompson's criterion by G. Kaplan and the second author, which recast it in terms of properties of sequences of Sylow subgroups and their products. This generalization also encompasses a possible characterization of the prosolvable radical whose scope of validity is still open even for finite groups. We prove that if this characterization is valid for finite groups, then it carries through to profinite groups.

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