Search results for "Nilpotent"

OnF-Subnormal Subgroups andF-Residuals of Finite Soluble Groups

1996

All groups that we consider are finite and soluble. Recall that a formation is a class of groups which is closed under homomorphic images and subdirect products. Hence, if F is a formation and G is a group which is a direct product of the subgroups A and B, then G is in F if and only if A and B lie in F. More generally, Doerk and w x Hawkes 4, IV, 1.18 proved that if G is a group such that G s A = B, then G s A = B , where G is the F-residual of G, that is, the smallest normal subgroup of G with quotient in F. The main purpose of this paper is the development of this result by means of the concept of F-subnormal subgroup. Suppose that F is a saturated formation. A maximal subgroup M of a Ž …

ARITHMETICAL QUESTIONS IN π-SEPARABLE GROUPS

2005

If G is a finite π-separable group, π a set of primes und X is a π-suhgroup of G, let vπ(G, X) be the number of Hall π-suhgroups of G containing X. If K is a subgroup of G containing X, we prove that vπ(K,X) divides vπ(G).

On 𝓕-subnormal subgroups and Frattini-like subgroups of a finite group

1994

Throughout the paper we consider only finite groups.J. C. Beidleman and H. Smith [3] have proposed the following question: “If G is a group and Ha subnormal subgroup of G containing Φ(G), the Frattini subgroup of G, such that H/Φ(G)is supersoluble, is H necessarily supersoluble? “In this paper, we give not only an affirmative answer to this question but also we see that the above result still holds if supersoluble is replaced by any saturated formation containing the class of all nilpotent groups.

On the WGSC Property in Some Classes of Groups

2009

The property of quasi-simple filtration (or qsf) for groups has been introduced in literature more than 10 years ago by S. Brick. This is equivalent, for groups, to the weak geometric simple connectivity (or wgsc). The main interest of these notions is that there is still not known whether all finitely presented groups are wgsc (qsf) or not. The present note deals with the wgsc property for solvable groups and generalized FC-groups. Moreover, a relation between the almost-convexity condition and the Tucker property, which is related to the wgsc property, has been considered for 3-manifold groups.

?-constraint with respect to a Fitting class

1986

Generic 3-parameter families of vector fields on the plane, unfolding a singularity with nilpotent linear part. The cusp case of codimension 3

1987

AbstractA cusp type germ of vector fields is a C∞ germ at 0∈ℝ2, whose 2-jet is C∞ conjugate toWe define a submanifold of codimension 5 in the space of germs consisting of germs of cusp type whose 4-jet is C0 equivalent toOur main result can be stated as follows: any local 3-parameter family in (0, 0) ∈ ℝ2 × ℝ3 cutting transversally in (0, 0) is fibre-C0 equivalent to

Fitting classes ℱ such that all finite groups have ℱ-injectors

1986

Let ℱ be an homomorph and Fitting class such thatEzℱ=ℱ. In this paper we prove that if all ℱ-constrained groups have ℱ-injectors, then all groups have ℱ-injectors. In particular if ℱ is a class of quasinilpotent groups containing the nilpotent groups, then every group has ℱ-injectors.

On Formations of Finite Groups with the Wielandt Property for Residuals

2001

Abstract Given two subgroups U, V of a finite group which are subnormal subgroups of their join 〈U, V〉 and a formation F , in general it is not true that 〈U, V〉 F  = 〈U F , V F 〉. A formation is said to have the Wielandt property if this equality holds universally. A formation with the Wielandt property must be a Fitting class. Wielandt proved that the most usual Fitting formations (e.g., nilpotent groups and π-groups) have the Wielandt property. At present, neither a general satisfactory result on the universal validity of the Wielandt property nor a counterexample is known. In this paper a criterion for a Fitting formation to have the Wielandt property is given. As an application, it is p…

Invariant characters and coprime actions on finite nilpotent groups

2000

Suppose that a group A acts via automorphisms on a nilpotent group G having coprime order. Given an A-invariant character \(\chi \in {\rm Irr}(G)\), we show that the A-primitive irreducible characters that induce \(\chi \) from an A-invariant subgroup of G all have equal degree. We use this result to obtain some information about the characters of groups of p-length 1.

Inducing characters and nilpotent subgroups

1996

If H H is a subgroup of a finite group G G and γ ∈ Irr ⁡ ( H ) \gamma \in \operatorname {Irr}(H) induces irreducibly up to G G , we prove that, under certain odd hypothesis, F ( G ) F ( H ) \mathbf {F}(G) \mathbf {F}(H) is a nilpotent subgroup of G G .