共查询到20条相似文献,搜索用时 15 毫秒
1.
Slobodan Tanushevski 《代数通讯》2013,41(10):4378-4410
For a given group G and a homomorphism ?: G → G × G, we construct groups ??(G), 𝒯?(G), and 𝒱?(G) that blend Thompson's groups F, T, and V with G, respectively. Furthermore, we describe the lattice of normal subgroups of the groups ?Δ(G), where Δ: G → G × G is the diagonal homomorphism, Δ(g) = (g, g). 相似文献
2.
Juan Carlos Martínez 《Topology and its Applications》2011,158(2):223-228
We show that the product of a subparacompact C-scattered space and a Lindelöf D-space is D. In addition, we show that every regular locally D-space which is the union of a finite collection of subparacompact spaces and metacompact spaces has the D-property. Also, we extend this result from the class of locally D-spaces to the wider class of D-scattered spaces. All the results are shown in a direct way. 相似文献
3.
Randall R. Holmes 《Linear and Multilinear Algebra》2004,52(2):133-143
Studied is an assumption on a group that ensures that no matter how the group is embedded in a symmetric group, the corresponding symmetrized tensor space has an orthogonal basis of standard (decomposable) symmetrized tensors. 相似文献
4.
Let G be a finite group and cs(G) be the set of conjugacy class sizes of G. In 1987, J. G. Thompson conjectured that, if G is a finite group with Z(G) = 1 and M is a nonabelian simple group satisfying that cs(G) = cs(M), then G ? M. This conjecture has been proved for Suzuki groups in [5]. In this article, we improve this result by proving that, if G is a finite group such that cs(G) = cs(Sz(q)), for q = 22m+1, then G ? Sz(q) × A, where A is abelian. We avoid using classification of finite simple groups in our proofs. 相似文献
5.
For a coinmutative senugoup (S, +, *) with involution and a function f : S → [0, ∞), the set S(f) of those p ≥ 0 such that fP is a positive definite function on S is a closed subsemigroup of [0, ∞) containing 0. For S = (IR, +, x* = -x) it may happen that S(f) = { kd : k ∈ N0 } for some d > 0, and it may happen that S(f) = {0} ? [d, ∞) for some d > O. If α > 2 and if S = (?, +, n* = -n) and f(n) = e?[n]α or S = (IN0, +, n* = n) and f(n) = enα, then S(f) ∪ (0, c) = ? and [d, ∞) ? S(f) for some d ≥; c > 0. Although (with c maximal and d minimal) we have not been able to show c = d in all cases, this equality does hold if S = ? and α ≥ 3.4. In the last section we give sinipler proofs of previously known results concerning the positive definiteness of x → e?||x||α on normed spaces. 相似文献
6.
Liang-Xue Peng 《Topology and its Applications》2008,155(6):522-526
In this note, we show that if X is the union of a finite collection of strong Σ-spaces, then X is a D-space. As a corollary, we get a conclusion that if X is the union of a finite collection of Moore spaces, then X is a D-space. This gives a positive answer to one of Arhangel'skii's problems [A.V. Arhangel'skii, D-spaces and finite unions, Proc. AMS 132 (7) (2004) 2163-2170]. In the last part of the note, we show that if X is the union of a finite collection of DC-like spaces, then X is a D-space, where DC is the class of all discrete unions of compact spaces. As a corollary, we show that if X is the union of a finite collection of regular subparacompact C-scattered spaces, then X is a D-space. 相似文献
7.
We study incidence properties among cosets of infinite loops, with emphasis on well‐structured varieties such as antiautomorphic loops and Bol loops. While cosets in groups are either disjoint or identical, we find that the incidence structure in general loops can be much richer. Every symmetric design, for example, can be realized as a canonical collection of cosets of a infinite loop. We show that in the variety of antiautomorphic loops the poset formed by set inclusion among intersections of left cosets is isomorphic to that formed by right cosets. We present an algorithm that, given a infinite Bol loop S, can in some cases determine whether |S| divides |Q| for all infinite Bol loops Q with S?Q, and even whether there is a selection of left cosets of S that partitions Q. This method results in a positive confirmation of Lagrange's Theorem for Bol loops for a few new cases of subloops. Finally, we show that in a left automorphic Moufang loop Q (in particular, in a commutative Moufang loop Q), two left cosets of S?Qare either disjoint or they intersect in a set whose cardinality equals that of some subloop of S. 相似文献
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This article derives the weak estimate of the first type for pentahedral finite elements over uniform partitions of the domain for the Poisson equation. The estimate for the W1,1‐seminorm of the discrete derivative Green's function is also given. Using these two estimates, we obtain the pointwise supercloseness of derivatives of the pentahedral finite element approximation and the interpolant to the true solution. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2010 相似文献
11.
Beifang Chen 《Discrete and Computational Geometry》1993,10(1):79-93
The Euler characteristic plays an important role in many subjects of discrete and continuous mathematics. For noncompact spaces,
its homological definition, being a homotopy invariant, seems not as important as its role for compact spaces. However, its
combinatorial definition, as a finitely additive measure, proves to be more applicable in the study of singular spaces such
as semialgebraic sets, finitely subanalytic sets, etc. We introduce an interesting integral by means of which the combinatorial
Euler characteristic can be defined without the necessity of decomposition and extension as in the traditional treatment for
polyhedra and finite unions of compact convex sets. Since finite unions of closed convex sets cannot be obtained by cutting
convex sets as in the polyhedral case, a separate treatment of the Euler characteristic for functions generated by indicator
functions of closed convex sets and relatively open convex sets is necessary, and this forms the content of this paper. 相似文献
12.
Positive Solutions of Second-order Difference Equation with Variable Coefficient on the Infinite Interval 下载免费PDF全文
In this paper, based on the one-signed Green''s function and the compact results on the infinite interval, we obtain the existence and multiplicity of positive solutions for the boundary value problems
\begin{align*}
\left\{\begin{array}{ll}
\Delta^2x(n-1)-p(n)\Delta x(n-1)-q(n)x(n-1)+f(n,x(n))=0, \ n\in\mathbb{N}, \\[0ex]
\alpha x(0)-\beta\Delta x(0)=0, \quad \ \ \lim\limits_{n\rightarrow\infty}x(n)=0
\end{array} \right.
\end{align*}
by the fixed point theorem in cones. The main results extend some results in the previous literature. 相似文献
13.
设$k$是一个弱维数有限的交换环, $G$是一个群. 本文讨论了群$G$具有有限的Gorenstein同调维数的标准.证明了群$G$的Gorenstein同调维数的有限性与群环$kG$的Gorenstein弱维数的有限性是一致的.进一步,我们给出了Serre定理的一个Gorenstein类比.推广了整环上$G$的Gorenstein同调维数的一些已知结果. 相似文献
14.
On automorphism groups of some finite groups 总被引:1,自引:0,他引:1
钱国华 《中国科学A辑(英文版)》2003,46(4):450-458
We show that if n > 1 is odd and has no divisor p4 for any prime p, then there is no finite group G such that│Aut(G)│ = n. 相似文献
15.
LetR be a ring. For the setF of all nonzero ideals ofR, we introduce an equivalence relation inF as follows: For idealsI andJ, I~J if and only ifV R (I)=V R(J), whereV R() is the centralizer inR. LetI R=F/~. Then we can see thatn(I R), the cardinality ofI R, is 1 if and only ifR is either a prime ring or a commutative ring (Theorem 1.1). An idealI ofR is said to be a commutator ideal ifI is generated by{st?ts; s∈S, t∈T} for subsetS andT ofR, andR is said to be a ring with (N) if any commutator ideal contains no nonzero nilpotent ideals. Then we have the following main theorem: LetR be a ring with (N). Thenn(I R) is finite if and only ifR is isomorphic to an irredundant subdirect sum ofS⊕Z whereS is a finite direct sum of non commutative prime rings andZ is a commutative ring (Theorem 2.1). Finally, we show that the existence of a ringR such thatn(I R)=m for any given natural numberm. 相似文献
16.
Da-Lun Wang 《Journal of Combinatorial Theory, Series A》1977,23(3):344-348
Let F be a family of subsets of an n-element set. F is said to be of type (n, r, s) if A ∈ F, B ∈ F implies that |A ∪ B| ? n ? r, and |A ∩ B| ? s. Let f(n, r, s) = max {|F| : F is of type (n, r, s)}. We prove that f(n, r, s) ? f(n ? 1, r ? 1, s) + f(n ? 1, r + 1, s) if r > 0, n > s. And this result is used to give simple and unified proofs of Katona's and Frankl's results on f(n, r, s) when s = 0 and s = 1. 相似文献
17.
Let ? be a complete set of Sylow subgroups of a finite group G, that is, a set composed of a Sylow p-subgroup of G for each p dividing the order of G. A subgroup H of G is called ?-S-semipermutable if H permutes with every Sylow p-subgroup of G in ? for all p?π(H); H is said to be ?-S-seminormal if it is normalized by every Sylow p-subgroup of G in ? for all p?π(H). The main aim of this paper is to characterize the ?-MS-groups, or groups G in which the maximal subgroups of every Sylow subgroup in ? are ?-S-semipermutable in G and the ?-MSN-groups, or groups in which the maximal subgroups of every Sylow subgroup in ? are ?-S-seminormal in G. 相似文献
18.
We prove some Trudinger-type inequalities and Brezis-Gallouet-Wainger inequality on the Heisenberg group, extending to this context the Euclidean results by T. Ozawa. 相似文献
19.
Jinghong Liu Gui Hu Qiding Zhu 《Numerical Methods for Partial Differential Equations》2013,29(3):1043-1055
For a variable coefficient elliptic boundary value problem in three dimensions, using the properties of the bubble function and the element cancelation technique, we derive the weak estimate of the first type for tetrahedral quadratic elements. In addition, the estimate for the W1,1‐seminorm of the discrete derivative Green's function is also given. Finally, we show that the derivatives of the finite element solution uh and the corresponding interpolant Π2u are superclose in the pointwise sense of the L∞‐norm. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013 相似文献
20.
Jason Howald Mircea Mustata Cornelia Yuen 《Proceedings of the American Mathematical Society》2007,135(11):3425-3433
We show that the real parts of the poles of the Igusa zeta function of a monomial ideal can be computed from the torus-invariant divisors on the normalized blow-up of the affine space along the ideal. Moreover, we show that every such number is a root of the Bernstein-Sato polynomial associated to the monomial ideal.