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1.
Let G be a finite group, and let p1,…, pm be the distinct prime divisors of |G|. Given a sequence 𝒫 =P1,…, Pm, of Sylow pi-subgroups of G, and g ∈ G, denote by m𝒫(g) the number of factorizations g = g1…gm such that gi ∈ Pi. The properly normalized average of m𝒫 over all 𝒫 is a complex character over G whose kernel contains the solvable radical of G [7]. The present paper characterizes the solvable residual of G in terms of this character. 相似文献
2.
Patrick W. Keef 《代数通讯》2013,41(10):3949-3968
A class 𝒳 of abelian p-groups is closed under ω1-bijective homomorphisms if whenever f: G → H is a homomorphism with countable kernel and cokernel, then G ∈ 𝒳 iff H ∈ 𝒳. For an ordinal α, we consider the smallest class with this property containing (a) the p α-bounded simply presented groups; (b) the p α-projective groups; (c) the subgroups of p α-bounded simply presented groups. This builds upon classical results of Nunke from [14] and [15]. Particular attention is paid to the separable groups in these classes. 相似文献
3.
Daniel Larsson 《代数通讯》2013,41(12):4303-4318
In this article we apply a method devised in Hartwig, Larsson, and Silvestrov (2006) and Larsson and Silvestrov (2005a) to the simple 3-dimensional Lie algebra 𝔰𝔩2(𝔽). One of the main points of this deformation method is that the deformed algebra comes endowed with a canonical twisted Jacobi identity. We show in the present article that when our deformation scheme is applied to 𝔰𝔩2(𝔽) we can, by choosing parameters suitably, deform 𝔰𝔩2(𝔽) into the Heisenberg Lie algebra and some other 3-dimensional Lie algebras in addition to more exotic types of algebras, this being in stark contrast to the classical deformation schemes where 𝔰𝔩2(𝔽) is rigid. 相似文献
4.
Morton E. Harris 《代数通讯》2013,41(8):3668-3671
At some point, after publication, the author realized that the proof of [3, Theorem 5.2] is incorrect. This proof incorrectly adapts the proof of [1, Theorem 4.8] since [3, (5.5)] is incorrect. Using the same proof outline, we correct the proof of [3, Theorem 5.2]. 相似文献
5.
We consider the class ? of finitely generated toral relatively hyperbolic groups. We show that groups from ? are commutative transitive and generalize a theorem proved by Benjamin Baumslag in [3] to this class. We also discuss two definitions of (fully) residually-𝒞 groups, i.e., the classical Definition 1.1 and a modified Definition 1.4. Building upon results obtained by Ol'shanskii [18] and Osin [22], we prove the equivalence of the two definitions for 𝒞 = ?. This is a generalization of the similar result obtained by Ol'shanskii for 𝒞 being the class of torsion-free hyperbolic groups. Let Γ ∈ ? be non-abelian and non-elementary. Kharlampovich and Miasnikov proved in [14] that a finitely generated fully residually-Γ group G embeds into an iterated extension of centralizers of Γ. We deduce from their theorem that every finitely generated fully residually-Γ group embeds into a group from ?. On the other hand, we give an example of a finitely generated torsion-free fully residually-? group that does not embed into a group from ?; ? is the class of hyperbolic groups. 相似文献
6.
Seyyed Majid Jafarian Amiri 《代数通讯》2013,41(6):2055-2059
In [1], the authors proved that the maximum sum of element orders on finite groups of the same order occurs in cyclic group. In this paper we obtain the structure of groups having maximum sum of element orders on noncyclic nilpotent group of the same order. 相似文献
7.
We show that the symplectic groups PSp6(q) are Hurwitz for all q = p m ≥ 5, with p an odd prime. The result cannot be improved since, for q even and q = 3, it is known that PSp6(q) is not Hurwitz. In particular, n = 6 turns out to be the smallest degree for which a family of classical simple groups of degree n, over 𝔽 p m , contains Hurwitz groups for infinitely many values of m. This fact, for a given (possibly large) p, also follows from [9] and [10]. 相似文献
8.
9.
Yi-Ming Zou 《代数通讯》2013,41(5):1529-1540
ABSTRACT Using the local subgroup strategy of An and O'Brien (1997), An and O'Brien (1999), we classify the radical subgroups and chains of the Fischer simple group Fi 22 and verify the Alperin weight conjecture and the Uno reductive conjecture for this group; the latter is a refinement of the Dade reductive and Isaacs–Navarro conjectures. 相似文献
10.
Peter V. Danchev 《代数通讯》2013,41(4):1461-1463
We show that in the article of Cutler and Missel (1984) there is, in fact, an example of an essentially finitely indecomposable (e.f.i.) abelian p-group which is not thick, and which can be chosen even to be separable, thus answering once again in the negative Irwin's conjecture that the e.f.i. p-groups are precisely the thick ones and that was already resolved in Dugas and Irwin (1992). 相似文献
11.
Samuel M. Corson 《代数通讯》2018,46(10):4317-4324
In this note we strengthen a result of Newman and use it to prove a conjecture of Nakamura stated in [10] that torsion-free one-relator groups are noncommutatively slender. 相似文献
12.
Seadat Ollah Faramarzi 《代数通讯》2013,41(12):4391-4415
In [5] Bruns and Gubeladze have constructed Milnor K 2-groups for so-called balanced lattice polytopes and classified the balanced polytopes of dimension 2 up to equivalence of the stable elementary groups 𝔼(R, P). In [6] they have shown that the polytopes in a certain subclass, called Col-divisible, behave well for the construction of higher K-groups. In this article, we give a list of all possibly occurring E-equivalence classes of three-dimensional balanced polytopes. Finally, we compute 𝔼(R, P) provided P is a Col-divisible balanced polytope of dimension three. 相似文献
13.
Five open questions on Goldie extending modules were posed by Akalan et al. [1]. The first one and the second one are considered in this article. It is shown that a 𝒢-extending module M with (C 3) is 𝒢+-extending. Moreover, let M = M 1 ⊕ M 2 be a direct sum of 𝒢-extending modules, where M satisfies (C 3) and M 1 is M 2-ojective (or M 2 is M 1-ojective), then M is 𝒢-extending. Other sufficient conditions for a direct sum of 𝒢-extending modules to be 𝒢-extending are obtained. 相似文献
14.
ABSTRACT Model theorists have made use of low-dimensional continuous cohomology of infinite permutation groups on profinite modules, see Ahlbrandt and Ziegler (1991), Evans (1997b), Evans et al. (1997), and Hodges and Pillay (1994), for example. We expand the module category in order to widen the cohomological toolkit. For an important class of groups we use these tools to establish criteria for finiteness of cohomology. 相似文献
15.
In [9] Giraldo and Merklen studied irreducible morphisms in the categories 𝒞(𝒜) and D?(Λ), where 𝒞(𝒜) is the category of complexes over an abelian Krull–Schmidt category 𝒜 and D?(Λ) is the derived category of the bounded above complexes of finite generate left modules, over an Artin algebra Λ. In this work, we continue the study of irreducible morphism having one finite irreducible truncation. 相似文献
16.
Joanna Meissner 《Numerical Functional Analysis & Optimization》2013,34(9):1035-1052
Let X = (C N [0, 1], ‖·‖), where N ≥ 3 and let V be a linear subspace of Π N , where Π N denotes the space of algebraic polynomials of degree less than or equal to N. Denote by 𝒫 S = 𝒫 S (X, V) = {P: X → V | P-linear and bounded P| V = id V , PS ? S}, where S denotes a cone of multi-convex functions. In [25, 26], the multi-convex projections were defined and it was shown the explicite formula for projection with minimal norm in 𝒫 S for V = Π N . In this article we present a generalization of these results in the case of V being certain, proper subspaces of Π N . 相似文献
17.
This article is a continuous work of [17], where the coauthors introduced the notion of 𝒢-FP-injective R-modules. In this article, we define a notion of 𝒢-FP-injective dimension for complexes over left coherent rings. To investigate the relationships between 𝒢-FP-injective dimension and FP-injective dimension for complexes, the complete cohomology group bases on FP-injectives is given. 相似文献
18.
A finite oscillator dictionary which has important applications in sequences designs and the compressive sensing was introduced by Gurevich, Hadani, and Sochen in [3]. In this paper, closed formulae of the finite split oscillator dictionary 𝔖 s are revisited by a simple proof, the structure of nonsplit tori of the group SL(2, 𝔽 p ) is studied, and an explicit algorithm for computing the finite nonsplit oscillator dictionary 𝔖 ns is described. 相似文献
19.
We consider three infinite families of cyclic presentations of groups, depending on a finite set of integers and having the same polynomial. Then we prove that the corresponding groups with the same parameters are isomorphic, and that the groups are almost all infinite. Finally, we completely compute the maximal Abelian quotients of such groups, and show that their HNN extensions are high-dimensional knot groups. Our results contain as particular cases the main theorems obtained in two nice articles: Johnson et al. (1999) and Havas et al. (2001). 相似文献
20.
In this paper, based on the results in [8] we give a monomial basis for q-Schur superalgebra and then a presentation for it. The presentation is different from that in [12]. Imitating [3] and [7], we define the infinitesimal and the little q-Schur superalgebras. We give a “weight idempotent presentation” for infinitesimal q-Schur superalgebras. The BLM bases and monomial bases of little q-Schur superalgebras are obtained, and dimension formulas of infinitesimal and little q-Schur superalgebras are deduced. 相似文献