On nontrivial factorisations of a one-generated local formation of finite groups

Author(s):  
A. N. Skiba
1990 ◽  
Vol 42 (2) ◽  
pp. 267-286 ◽  
Author(s):  
Peter Förster

We study the following question: given any local formation of finite groups, do there exist maximal local subformations? An answer is given by providing a local definition of the intersection of all maximal local subformations.


1985 ◽  
Vol 31 (1) ◽  
pp. 5-34 ◽  
Author(s):  
P. Förster ◽  
E. Salomon

It is well known that every local formation of finite soluble groups possesses three distinguished local definitions consisting of finite soluble groups: the minimal one, the full and integrated one, and the maximal one. As far as the first and the second of these are concerned, this statement remains true in the context of arbitrary finite groups. Doerk, Šemetkov, and Schmid have posed the problem of whether every local formation of finite groups has a distinguished (that is, unique) maximal local definition. In this paper a description of local formations with a unique maximal local definition is given, from which counter-examples emerge. Furthermore, a criterion for a formation function to be a local definition of a given local formation is obtained.


Author(s):  
Aleksandr Tsarev

Let [Formula: see text] be a class of simple groups with a completeness property [Formula: see text]. Förster introduced the concept of [Formula: see text]-local formation in order to obtain a common extension of well-known theorems of Gaschütz–Lubeseder–Schmid and Baer [Publ. Mat. UAB 29(2–3) (1985) 39–76]. In this paper, it is proved that the lattice of all [Formula: see text]-local formations of finite groups is modular.


Author(s):  
Ruslan V. Borodich

In the work of Beidleman and Smith [On Frattini-like subgroups, Glasgow Math. J. 35 (1993) 95–98], the following question was raised: “If [Formula: see text] is a subnormal subgroup of a finite group [Formula: see text] containing [Formula: see text], then whether the supersolvability of [Formula: see text] follows the supersolvability of [Formula: see text]”. This problem was considered in works of Selkin [Maximal Subgroups in the Theory of Classes of Finite Groups (Belaruskaya, Navuka, 1997)], Skiba [On the intersection of all maximal [Formula: see text]-subgroups of a finite group, Prob. Phys. Math. Tech. 3(4) (2010) 56–62], Ballester-Bolinches [On [Formula: see text]-subnormal subgroups and Frattini-like subgroups of a finite group, Glasgow Math. J. 36 (1994) 241–247] and many other authors (see monograph [Maximal Subgroups in the Theory of Classes of Finite Groups (Belaruskaya, Navuka, 1997)]). In this paper, we give the answer to the more general question: “Let [Formula: see text] be a local formation. If [Formula: see text] is a subnormal subgroup of a group [Formula: see text], then in what case [Formula: see text] will follow from [Formula: see text]”.


2010 ◽  
Vol 87 (1-2) ◽  
pp. 258-263 ◽  
Author(s):  
Xiaolan Yi ◽  
L. A. Shemetkov

2008 ◽  
Vol 01 (04) ◽  
pp. 619-629 ◽  
Author(s):  
Nanying Yang ◽  
Wenbin Guo

Let G be a finite group and denote a formation of finite groups by [Formula: see text]. We call a subgroup H of G[Formula: see text]-supplemented in G if there exists a normal subgroup K of G such that G = HK and (H ∩ K)HG/HG is contained in the [Formula: see text]-hypercenter [Formula: see text] of G/HG. In this paper, we use [Formula: see text]-supplemented subgroups to study the structure of finite groups. Some known results in the literature are generalized.


2008 ◽  
Vol 78 (1) ◽  
pp. 97-106
Author(s):  
GIL KAPLAN ◽  
DAN LEVY

AbstractLet α be a formation of finite groups which is closed under subgroups and group extensions and which contains the formation of solvable groups. Let G be any finite group. We state and prove equivalences between conditions on chief factors of G and structural characterizations of the α-residual and theα-radical of G. We also discuss the connection of our results to the generalized Fitting subgroup of G.


Sign in / Sign up

Export Citation Format

Share Document