scholarly journals A Note on the Normal Index and thec-Section of Maximal Subgroups of a Finite Group

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Na Tang ◽  
Xianhua Li

LetMbe a maximal subgroup of finite groupG. For each chief factorH/KofGsuch thatK≤MandG=MH, we called the order ofH/Kthe normal index ofMandM∩H/Ka section ofMinG. Using the concepts of normal index andc-section, we obtain some new characterizations ofp-solvable, 2-supersolvable, andp-nilpotent.

Mathematics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 2165
Author(s):  
Abd El-Rahman Heliel ◽  
Mohammed Al-Shomrani ◽  
Adolfo Ballester-Bolinches

Let σ={σi:i∈I} be a partition of the set P of all prime numbers and let G be a finite group. We say that G is σ-primary if all the prime factors of |G| belong to the same member of σ. G is said to be σ-soluble if every chief factor of G is σ-primary, and G is σ-nilpotent if it is a direct product of σ-primary groups. It is known that G has a largest normal σ-nilpotent subgroup which is denoted by Fσ(G). Let n be a non-negative integer. The n-term of the σ-Fitting series of G is defined inductively by F0(G)=1, and Fn+1(G)/Fn(G)=Fσ(G/Fn(G)). If G is σ-soluble, there exists a smallest n such that Fn(G)=G. This number n is called the σ-nilpotent length of G and it is denoted by lσ(G). If F is a subgroup-closed saturated formation, we define the σ-F-lengthnσ(G,F) of G as the σ-nilpotent length of the F-residual GF of G. The main result of the paper shows that if A is a maximal subgroup of G and G is a σ-soluble, then nσ(A,F)=nσ(G,F)−i for some i∈{0,1,2}.


2018 ◽  
Vol 21 (3) ◽  
pp. 463-473
Author(s):  
Viachaslau I. Murashka

Abstract Let {\mathfrak{X}} be a class of groups. A subgroup U of a group G is called {\mathfrak{X}} -maximal in G provided that (a) {U\in\mathfrak{X}} , and (b) if {U\leq V\leq G} and {V\in\mathfrak{X}} , then {U=V} . A chief factor {H/K} of G is called {\mathfrak{X}} -eccentric in G provided {(H/K)\rtimes G/C_{G}(H/K)\not\in\mathfrak{X}} . A group G is called a quasi- {\mathfrak{X}} -group if for every {\mathfrak{X}} -eccentric chief factor {H/K} and every {x\in G} , x induces an inner automorphism on {H/K} . We use {\mathfrak{X}^{*}} to denote the class of all quasi- {\mathfrak{X}} -groups. In this paper we describe all hereditary saturated formations {\mathfrak{F}} containing all nilpotent groups such that the {\mathfrak{F}^{*}} -hypercenter of G coincides with the intersection of all {\mathfrak{F}^{*}} -maximal subgroups of G for every group G.


1964 ◽  
Vol 16 ◽  
pp. 435-442 ◽  
Author(s):  
Joseph Kohler

In this paper finite groups with the property M, that every maximal subgroup has prime or prime square index, are investigated. A short but ingenious argument was given by P. Hall which showed that such groups are solvable.B. Huppert showed that a finite group with the property M, that every maximal subgroup has prime index, is supersolvable, i.e. the chief factors are of prime order. We prove here, as a corollary of a more precise result, that if G has property M and is of odd order, then the chief factors of G are of prime or prime square order. The even-order case is different. For every odd prime p and positive integer m we shall construct a group of order 2apb with property M which has a chief factor of order larger than m.


1970 ◽  
Vol 3 (2) ◽  
pp. 273-276
Author(s):  
John Randolph

Let G be a finite group with a nilpotent maximal subgroup S and let P denote the 2-Sylow subgroup of S. It is shown that if P ∩ Q is a normal subgroup of P for any 2-Sylow subgroup Q of G, then G is solvable.


2018 ◽  
Vol 25 (04) ◽  
pp. 579-584
Author(s):  
Chi Zhang ◽  
Wenbin Guo ◽  
Natalia V. Maslova ◽  
Danila O. Revin

For a positive integer n, we denote by π(n) the set of all prime divisors of n. For a finite group G, the set [Formula: see text] is called the prime spectrum of G. Let [Formula: see text] mean that M is a maximal subgroup of G. We put [Formula: see text] and [Formula: see text]. In this notice, using well-known number-theoretical results, we present a number of examples to show that both K(G) and k(G) are unbounded in general. This implies that the problem “Are k(G) and K(G) bounded by some constant k?”, raised by Monakhov and Skiba in 2016, is solved in the negative.


2014 ◽  
Vol 57 (2) ◽  
pp. 277-282 ◽  
Author(s):  
A. M. Elkholy ◽  
M. H. Abd El-Latif

AbstractLet G be a finite group and H, K two subgroups of G. A group G is said to be a mutually m-permutable product of H and K if G = HK and every maximal subgroup of H permutes with K and every maximal subgroup of K permutes with H. In this paper, we investigate the structure of a finite group that is a mutually m-permutable product of two subgroups under the assumption that its maximal subgroups are totally smooth.


2020 ◽  
Vol 8 ◽  
Author(s):  
ANDREA LUCCHINI ◽  
CLAUDE MARION ◽  
GARETH TRACEY

For a finite group $G$ , let $d(G)$ denote the minimal number of elements required to generate $G$ . In this paper, we prove sharp upper bounds on $d(H)$ whenever $H$ is a maximal subgroup of a finite almost simple group. In particular, we show that $d(H)\leqslant 5$ and that $d(H)\geqslant 4$ if and only if $H$ occurs in a known list. This improves a result of Burness, Liebeck and Shalev. The method involves the theory of crowns in finite groups.


2019 ◽  
Vol 18 (05) ◽  
pp. 1950087
Author(s):  
Xiaolan Yi ◽  
Shiyang Jiang ◽  
S. F. Kamornikov

The subgroup structure of a finite group, under the assumption that its every non-nilpotent maximal subgroup has prime index, is studied in the paper.


1971 ◽  
Vol 23 (3) ◽  
pp. 550-552
Author(s):  
John W. Randolph

Throughout this paper G will denote a finite group containing a nilpotent maximal subgroup S and P will denote the Sylow 2-subgroup of S. The largest subgroup of S normal in G will be designated by core (S) and the largest solvable normal subgroup of G by rad(G). All other notation is standard.Thompson [6] has shown that if P = 1 then G is solvable. Janko [3] then observed that G is solvable if P is abelian, a condition subsequently weakened by him [4] to the assumption that the class of P is ≦ 2 . Our purpose is to demonstrate the sufficiency of a still weaker assumption about P.


2012 ◽  
Vol 86 (2) ◽  
pp. 291-302
Author(s):  
BARBARA BAUMEISTER ◽  
GIL KAPLAN

Abstractc-Sections of maximal subgroups in a finite group and their relation to solvability have been extensively researched in recent years. A fundamental result due to Wang [‘C-normality of groups and its properties’, J. Algebra 180 (1998), 954–965] is that a finite group is solvable if and only if the c-sections of all its maximal subgroups are trivial. In this paper we prove that if for each maximal subgroup of a finite group G, the corresponding c-section order is smaller than the index of the maximal subgroup, then each composition factor of G is either cyclic or isomorphic to the O’Nan sporadic group (the converse does not hold). Furthermore, by a certain ‘refining’ of the latter theorem we obtain an equivalent condition for solvability. Finally, we provide an existence result for large subgroups in the sense of Lev [‘On large subgroups of finite groups’ J. Algebra 152 (1992), 434–438].


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