共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
A subgroup H of a finite group G is called ℙ-subnormal in G whenever H either coincides with G or is connected to G by a chain of subgroups of prime indices. If every Sylow subgroup of G is ℙ-subnormal in G then G is called a w-supersoluble group. We obtain some properties of ℙ-subnormal subgroups and the groups that are products of two ℙ-subnormal subgroups, in particular,
of ℙ-subnormal w-supersoluble subgroups. 相似文献
3.
L. Di Terlizzi 《Acta Mathematica Hungarica》2009,124(4):399-401
We considered in Example 3.1 of the paper [1] an S-structure on R2n+s
. We concluded that when s > 1 this manifold cannot be of constant φ-sectional curvature. Unfortunately this result is wrong. In fact, essentially due
to a sign mistake in defining the φ-structure and a consequent transposition of the elements of the φ-basis (3.2), some of
the Christoffel’s symbols were incorrect. In the present rectification, using a more slendler tecnique, we prove that our
manifold is of constant φ-sectional curvature −3s and then it is η-Einstein. 相似文献
5.
We show that for any complete connected Kähler manifold, the index of the group of complex affine transformations in the group of c-projective transformations is at most two unless the Kähler manifold is isometric to complex projective space equipped with a positive constant multiple of the Fubini–Study metric. This establishes a stronger version of the recently proved Yano–Obata conjecture for complete Kähler manifolds. 相似文献
6.
7.
Let G be a simple algebraic group of type G2 over an algebraically closed field of characteristic 2. We give an example of a finite group Γ with Sylow 2-subgroup Γ2 and an infinite family of pairwise non-conjugate homomorphisms ρ: Γ → G whose restrictions to Γ2 are all conjugate. This answers a question of Burkhard Külshammer from 1995. We also give an action of Γ on a connected unipotent group V such that the map of 1-cohomologies H1(Γ, V) → H1(Γp, V) induced by restriction of 1-cocycles has an infinite fibre. 相似文献
8.
9.
10.
Let G be a finite group and π be a set of primes. Put ${d_{\pi}(G) = k_{\pi}(G)/|G|_{\pi}}$ , where ${k_{\pi}(G)}$ is the number of conjugacy classes of π-elements in G and |G| π is the π-part of the order of G. In this paper we initiate the study of this invariant by showing that if ${d_{\pi}(G) > 5/8}$ then G possesses an abelian Hall π-subgroup, all Hall π-subgroups of G are conjugate, and every π-subgroup of G lies in some Hall π-subgroup of G. Furthermore, we have ${d_{\pi}(G) = 1}$ or ${d_{\pi}(G) = 2/3}$ . This extends and generalizes a result of W. H. Gustafson. 相似文献
11.
12.
A subgroup H of a group G is said to be K-?-subnormal in G if H can be joined to the group by a chain of subgroups each of which is either normal in the next subgroup or of prime index in it. Properties of K-?-subnormal subgroups are obtained. A class of finite groups whose Sylow p-subgroups are K-?-subnormal in G for every p in a given set of primes is studied. Some products of K-?-subnormal subgroups are investigated. 相似文献
13.
We call a subgroup H of a finite group G c-supplemented in G if there exists a subgroup K of G such that G = HK and H ∩ K ≤ core(H). In this paper it is proved that a finite group G is p-nilpotent if G is S4-free and every minimal subgroup of P n GN is c-supplemented in NG(P), and when p = 2 P is quaternion-free, where p is the smallest prime number dividing the order of G, P a Sylow p-subgroup of G. As some applications of this result, some known results are generalized. 相似文献
14.
Let G be a finite abelian group. The Erd?s-Ginzburg-Ziv constant s(G) of G is defined as the smallest integer l∈N such that every sequence S over G of length |S|?l has a zero-sum subsequence T of length |T|=exp(G). If G has rank at most two, then the precise value of s(G) is known (for cyclic groups this is the theorem of Erd?s-Ginzburg-Ziv). Only very little is known for groups of higher rank. In the present paper, we focus on groups of the form , with n,r∈N and n?2, and we tackle the study of s(G) with a new approach, combining the direct problem with the associated inverse problem. 相似文献
15.
16.
We point out an error in the paper (Monatsh Math. doi:10.1007/s00605-013-0492-3, 2013) by Kang, and give new brief proofs of the main results. 相似文献
17.
Ibrahima Tounkara 《Comptes Rendus Mathematique》2018,356(4):360-364
A slice of finite groups is a pair consisting of a finite group G and a subgroup S of G. In this paper, we show that some properties of finite groups extend to slices of finite groups. In particular, by analogy with B-groups, we introduce the notion of -slice, and show that any slice of finite groups admits a largest quotient -slice. 相似文献
18.
K. Castillo 《Integral Transforms and Special Functions》2017,28(11):859-875
We study the Christoffel and Geronimus transformations for Laguerre–Hahn orthogonal polynomials on the real line. It is analysed the modification on the corresponding difference-differential equations that characterize the systems of orthogonal polynomials and the consequences for the three-term recurrence relation coefficients. 相似文献
19.
Aequationes mathematicae - A.M. Kagan introduced a class of distributions $$\mathcal {D}_{m, k}$$ in $$\mathbb {R}^m$$ and proved that if the joint distribution of m linear forms of n independent... 相似文献
20.
Marius T?rn?uceanu 《Central European Journal of Mathematics》2013,11(2):376-377
In this short note a correct proof of Theorem 3.3 from [T?rn?uceanu M., Solitary quotients of finite groups, Cent. Eur. J. Math., 2012, 10(2), 740–747] is given. 相似文献