scholarly journals Bounds on the fitting length of finite soluble groups with supersoluble Sylow normalisers

1991 ◽  
Vol 44 (1) ◽  
pp. 19-31 ◽  
Author(s):  
R.A. Bryce ◽  
V. Fedri ◽  
L. Serena
Keyword(s):  
Soluble Group ◽  
Chief Factor ◽  
Structural Constraints ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
Fitting Length

We prove that, in a finite soluble group, all of whose Sylow normalisers are super-soluble, the Fitting length is at most 2m + 2, where pm is the highest power of the smallest prime p dividing |G/Gs| here Gs is the supersoluble residual of G. The bound 2m + 2 is best possible. However under certain structural constraints on G/GS, typical of the small examples one makes by way of experimentation, the bound is sharply reduced. More precisely let p be the smallest, and r the largest, prime dividing the order of a group G in the class under consideration. If a Sylow p–subgroup of G/GS acts faithfully on every r-chief factor of G/GS, then G has Fitting length at most 3.

scholarly journals Cover-Avoidance Properties in Finite Soluble Groups

1976 ◽  
Vol 19 (2) ◽  
pp. 213-216 ◽  
Author(s):  
M. J. Tomkinson
Keyword(s):  
Soluble Group ◽  
Chief Factor ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
General Method

AbstractWe give a general method for constructing subgroups which either cover or avoid each chief factor of the finite soluble group G. A strongly pronorrnal subgroup V, a prefrattini subgroup W, an -normalizer D and intersections and products of V, W, and D axe all constructable. The constructable subgroups can be characterized by their cover-avoidance property and a permutability condition as in the results of J. D. Gillam [4] for prefrattini subgroups and -normalizers.

scholarly journals On a relation between the Fitting length of a soluble group and the number of conjugacy classes of its maximal nilpotent subgroups

1969 ◽  
Vol 1 (1) ◽  
pp. 3-10 ◽  
Author(s):  
H. Lausch ◽  
A. Makan
Keyword(s):  
Soluble Group ◽  
Conjugacy Classes ◽  
Finite Soluble Group ◽  
Prime Divisors ◽  
Soluble Groups ◽  
Odd Order ◽  
Fitting Length ◽  
Qualitative Nature ◽  
Positive Integers

In a finite soluble group G, the Fitting (or nilpotency) length h(G) can be considered as a measure for how strongly G deviates from being nilpotent. As another measure for this, the number v(G) of conjugacy classes of the maximal nilpotent subgroups of G may be taken. It is shown that there exists an integer-valued function f on the set of positive integers such that h(G) ≦ f(v(G)) for all finite (soluble) groups of odd order. Moreover, if all prime divisors of the order of G are greater than v(G)(v(G) - l)/2, then h(G) ≦3. The bound f(v(G)) is just of qualitative nature and by far not best possible. For v(G) = 2, h(G) = 3, some statements are made about the structure of G.

scholarly journals On a relation between injectors and certain complemented chief factors of finite soluble groups

1974 ◽  
Vol 17 (4) ◽  
pp. 385-388
Author(s):  
A. R. Makan
Keyword(s):  
Soluble Group ◽  
Fitting Class ◽  
Chief Factor ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
Chief Factors

The Fitting class of finite soluble π-groups, where π is an arbitrary set of primes, has the property that each complement of an -avoided, complemented chief factor of any finite soluble group G contains an -injector of G. In other words, each -avoided, complemented chief factor of G is -complemented in the sense of Hartley (see [2]).

Another characteristic conjugacy class of subgroups of finite soluble groups

1970 ◽  
Vol 11 (4) ◽  
pp. 395-400 ◽  
Author(s):  
A. Makan
Keyword(s):  
Normal Subgroup ◽  
Conjugacy Class ◽  
Soluble Group ◽  
Fitting Class ◽  
Chief Factor ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
Normal Product

Let name be a class of finite soluble groups with the properties: (1) is a Fitting class (i.e. normal subgroup closed and normal product closed) and (2) if N ≦ H ≦ G ∈, N ⊲ G and H/N is a p-group for some prime p, then H ∈. Then is called a Fischer class. In any finite soluble group G, there exists a unique conjugacy class of maximal -subgroups V called the -injectors which have the property that for every N◃◃G, N ∩ V is a maximal -subgroup of N [3]. 3. By Lemma 1 (4) [7] an -injector V of G covers or avoids a chief factor of G. As in [7] we will call a chief factor -covered or -avoided according as V covers or avoids it and -complemented if it is complemented and each of its complements contains some -injector. Furthermore we will call a chief factor partially-complemented if it is complemented and at least one of its complements contains some -injector of G.

scholarly journals Subgroups like Wielandt's in soluble groups

2000 ◽  
Vol 42 (1) ◽  
pp. 67-74 ◽  
Author(s):  
Clara Franchi
Keyword(s):  
Soluble Group ◽  
Subject Classification ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
Subnormal Subgroups

For each m≥1, u_{m}(G) is defined to be the intersection of the normalizers of all the subnormal subgroups of defect at most m in G. An ascending chain of subgroups u_{m,i}(G) is defined by setting u_{m,i}(G)/u_{m,i−1}(G)=u_{m}(G/u_{m,i−1}(G)). If u_{m,n}(G)=G, for some integer n, the m-Wielandt length of G is the minimal of such n.In [3], Bryce examined the structure of a finite soluble group with given m-Wielandt length, in terms of its polynilpotent structure. In this paper we extend his results to infinite soluble groups.1991 Mathematics Subject Classification. 20E15, 20F22.

scholarly journals On complemented chief factors of finite soluble groups

1972 ◽  
Vol 7 (1) ◽  
pp. 101-104 ◽  
Author(s):  
D.W. Barnes
Keyword(s):  
Soluble Group ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
Chief Factors ◽  
One To One

Let G = H0 > H1 > … > Hr = 1 and G = K0 > K1 > … > Kr =1 be two chief series of the finite soluble group G. Suppose Mi complements Hi/Hi+1. Then Mi also complements precisely one factor Kj/Kj+1, of the second series, and this Kj/Kj+1 is G-isomorphic to Hi/Hi+1. It is shown that complements Mi can be chosen for the complemented factors Hi/Hi+1 of the first series in such a way that distinct Mi complement distinct factors of the second series, thus establishing a one-to-one correspondence between the complemented factors of the two series. It is also shown that there is a one-to-one correspondence between the factors of the two series (but not in general constructible in the above manner), such that corresponding factors are G-isomorphic and have the same number of complements.

Finite soluble groups admitting an automorphism of prime power order with few fixed points

1987 ◽  
Vol 102 (3) ◽  
pp. 431-441 ◽  
Author(s):  
Brian Hartley ◽  
Volker Turau
Keyword(s):  
Fixed Points ◽  
Soluble Group ◽  
Prime Power ◽  
Prime Power Order ◽  
Finite Soluble Group ◽  
Prime Divisors ◽  
Fitting Subgroup ◽  
Soluble Groups ◽  
Fitting Height ◽  
Number Of Prime Divisors

Let G be a finite soluble group with Fitting subgroup F(G). The Fitting series of G is defined, as usual, by F0(G) = 1 and Fi(G)/Fi−1(G) = F(G/Fi−1(G)) for i ≥ 1, and the Fitting height h = h(G) of G is the least integer such that Fn(G) = G. Suppose now that a finite soluble group A acts on G. Let k be the composition length of A, that is, the number of prime divisors (counting multiplicities) of |A|. There is a certain amount of evidence in favour of theCONJECTURE. |G:Fk(G)| is bounded by a number depending only on |A| and |CG(A)|.

scholarly journals Groups of odd order in which every subnormal subgroup has defect at most two

1991 ◽  
Vol 51 (2) ◽  
pp. 331-342
Author(s):  
John Cossey
Keyword(s):  
Soluble Group ◽  
Subnormal Subgroup ◽  
Finite Soluble Group ◽  
Derived Length ◽  
Odd Order ◽  
Fitting Length

AbstractIn 1980, McCaughan and Stonehewer showed that a finite soluble group in which every subnormal subgroup has defect at most two has derived length at most nine and Fitting length at most five, and gave an example of derived length five and Fitting length four. In 1984 Casolo showed that derived length five and Fitting length four are best possible bounds.In this paper we show that for groups of odd order the bounds can be improved. A group of odd order with every subnormal subgroup of defect at most two has derived and Fitting length at most three, and these bounds are best possible.

scholarly journals Hypercentral injectors in infinite soluble groups

1979 ◽  
Vol 22 (3) ◽  
pp. 191-194 ◽  
Author(s):  
M. J. Tomkinson
Keyword(s):  
Finite Index ◽  
Soluble Group ◽  
Conjugacy Classes ◽  
Finite Soluble Group ◽  
Covering Property ◽  
Soluble Groups ◽  
Finite Case

The Carter subgroups of a finite soluble group may be characterised either as theself-normalising nilpotent subgroups or as the nilpotent projectors. Subgroups with properties analogous to both of these have been considered by Newell (2, 3) in the class of -groups. The results obtained are necessarily less satisfactory than in the finite case, the subgroups either being almost self-normalising (i.e. having finite index in their normaliser) or having an almost-covering property. Also the subgroups are not necessarily conjugate but lie in finitely many conjugacy classes.

A note on system normalizers of a finite soluble group

1966 ◽  
Vol 62 (3) ◽  
pp. 339-346 ◽  
Author(s):  
T. O. Hawkes
Keyword(s):  
Soluble Group ◽  
Partial Answer ◽  
Finite Soluble Group ◽  
Soluble Groups ◽  
Sylow Subgroups ◽  
Chief Factors ◽  
A Chain

Introduction. Hall ((3), (4)) introduced the concept of a Sylow system and its normalizer into the theory of finite soluble groups. In (4) he showed that system normalizers may be characterized as those subgroups D of G minimal subject to the existence of a chain of subgroups from D up to G in which each subgroup is maximal and non-normal in the next; he also showed that a system normalizer covers all the central chief factors and avoids all the eccentric chief factors of G (for definitions of covering and avoidance, and an account of their elementary properties), the reader is referred to Taunt ((5)). This note arises out of an investigation into the question to what extent this covering/ avoidance property characterizes system normalizers; it provides a partial answer by means of two elementary counter-examples given in section 3 which seem to indicate that the property ceases to characterize system normalizers as soon as the ‘non-commutativity’ of the group is increased beyond a certain threshold. For the sake of completeness we include proofs in Theorems 1 and 2 of generalizations of two known results communicated to me by Dr Taunt and which as far as we know have not been published elsewhere. Theorem 1 shows the covering/avoidance property to be characteristic for the class of soluble groups with self-normalizing system normalizers introduced by Carter in (1), while Theorem 2 shows the same is true for A -groups (soluble groups with Abelian Sylow subgroups investigated by Taunt in (5)).

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