共查询到20条相似文献,搜索用时 339 毫秒
1.
S. Garcia-Ferreira A. H. Tomita S. Watson 《Proceedings of the American Mathematical Society》2005,133(3):937-943
We prove that the existence of a selective ultrafilter on implies the existence of a countably compact group without non-trivial convergent sequences all of whose powers are countably compact. Hence, by using a selective ultrafilter on , it is possible to construct two countably compact groups without non-trivial convergent sequences whose product is not countably compact.
2.
Douglas Lind 《Proceedings of the American Mathematical Society》2005,133(5):1411-1416
We formulate Lehmer's Problem concerning the Mahler measure of polynomials for general compact abelian groups, introducing a Lehmer constant for each such group. We show that all nontrivial connected compact groups have the same Lehmer constant and conjecture the value of the Lehmer constant for finite cyclic groups. We also show that if a group has infinitely many connected components, then its Lehmer constant vanishes.
3.
Raushan Z. Buzyakova 《Topology and its Applications》2010,157(14):2289-161
We show that if X is countably compact but not compact then one can find a compact space K such that X⊕K does not embed closedly into any normal topological group. 相似文献
4.
Wieslaw Kubis Vladimir Uspenskij 《Proceedings of the American Mathematical Society》2005,133(8):2483-2487
A compact space is Valdivia compact if it can be embedded in a Tikhonov cube in such a way that the intersection is dense in , where is the sigma-product ( the set of points with countably many non-zero coordinates). We show that there exists a compact connected Abelian group of weight which is not Valdivia compact, and deduce that Valdivia compact spaces are not preserved by open maps.
5.
It is shown within Bishop's constructive mathematics that, under one extra, classically automatic, hypothesis, a continuous homomorphism from R onto a compact metric abelian group is periodic, but that the existence of the minimum value of the period is not derivable (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
In the compact group of galaxies the galaxies can merge into a few massive ones in a very short time, so they must be formed
very recently. On the other hand, according to the theory of structure formation, the denser system should form earlier. By
analyzing the apparent paradox, we suggest that the merging process of CDM halo plays an important role in the formation of
the compact groups of galaxies: it delays the formation of compact groups of galaxies, and makes the pups of galaxies much
denser.
Project partially supporter1 hy the Ministry of Science and Technology (of China). 相似文献
7.
In this paper, we prove the Donoho–Stark uncertainty principle for locally compact quantum groups and characterize the minimizer which are bi-shifts of group-like projections. We also prove the Hirschman–Beckner uncertainty principle for compact quantum groups and discrete quantum groups. Furthermore, we show Hardy's uncertainty principle for locally compact quantum groups in terms of bi-shifts of group-like projections. 相似文献
8.
双随机矩阵有许多重要的应用, 紧图族可以看作是组合矩阵论中关于双随机矩阵的著名的Birkhoff定理的拓广,具有重要的研究价值. 确定一个图是否紧图是个困难的问题,目前已知的紧图族尚且不多.给出了两个重要结果:任意紧图与任意多个孤立点的不交并是紧图;任意紧图的每一个顶点上各增加一条悬挂边的图是紧图. 利用这两个结果,从已知紧图可构造出无穷多个紧图族. 相似文献
9.
For solving complex flow field with multi-scale structure higher order accurate schemes are preferred. Among high order schemes
the compact schemes have higher resolving efficiency. When the compact and upwind compact schemes are used to solve aerodynamic
problems there are numerical oscillations near the shocks. The reason of oscillation production is because of non-uniform
group velocity of wave packets in numerical solutions. For improvement of resolution of the shock a parameter function is
introduced in compact scheme to control the group velocity. The newly developed method is simple. It has higher accuracy and
less stencil of grid points 相似文献
10.
Oleg Pavlov 《Proceedings of the American Mathematical Society》2001,129(9):2771-2775
We construct an example of a normal countably compact not absolutely countably compact space. We also prove that every hereditarily normal countably compact space is absolutely countably compact and suggest a method for construction of hereditarily normal spaces without property .
11.
Osamu Hatori 《Proceedings of the American Mathematical Society》1998,126(8):2351-2353
Every bounded regular Borel measure on noncompact LCA groups is a sum of an absolutely continuous measure and a measure with natural spectrum. The set of bounded regular Borel measures with natural spectrum on a nondiscrete LCA group whose Fourier-Stieltjes transforms vanish at infinity is closed under addition if and only if is compact.
12.
Artur Hideyuki Tomita 《Topology and its Applications》2005,150(1-3):197-205
We show the existence of a p-compact group whose size has countable cofinality in a forcing model. As a corollary, we show that consistently there exists a countably compact group whose size has countable cofinality and its weight is larger than the size. 相似文献
13.
14.
Given a C^*-algebra A and a comultiplication Ф on A, we show that the pair (A, Ф) is a compact quantum group if and only if the associated multiplier Hopf ^*-algebra (A, ФA) is a compact Hopf ^*-algebra. 相似文献
15.
Desmond Robbie Sergey Svetlichny 《Proceedings of the American Mathematical Society》1996,124(1):325-330
It is shown under CH that there exists a countably compact topological semigroup with two-sided cancellation which is not a topological group. Wallace's question" of 40 years standing is thus settled in the negative unless CH is explicitly denied. The example is a topological subsemigroup of an uncountable product of circle groups.
16.
Daniel Maier 《Mathematische Nachrichten》2015,288(8-9):968-983
By the classical Halmos‐von Neumann theorem, each compact monothetic group corresponds to an ergodic dynamical system with discrete spectrum. For such groups we prove two results. We first construct a compact monothetic group which does not split into a direct product of a connected and a totally disconnected compact monothetic group. Then we present a measure preserving dynamical system on the unit square being isomorphic to a rotation on this indecomposable group. 相似文献
17.
E. A. Gorin 《Mathematical Notes》2000,68(2):167-172
The existence of homeomorphisms establishign an isometry of normalized Haar measures on (metrizable) compact groups is studied.
In the case of 0-dimensional groups, a complete answer is given in terms of the indices of open normal subgroups. For example,
for the countable powers of the groups ℤ/(m) and ℤ/(n), the answer is affirmative if and only ifm andn have the same prime divisors. A certain class of extensions of 0-dimensional groups is also studied.
Translated fromMatematicheskie Zametki, Vol. 68, No. 2, pp. 188–194, August, 2000. 相似文献
18.
Mark Mandelkern 《Mathematical Logic Quarterly》1993,39(1):213-216
Although classically every open subspace of a locally compact space is also locally compact, constructively this is not generally true. This paper provides a locally compact remetrization for an open set in a compact metric space and constructs a one-point compactification. MSC: 54D45, 03F60, 03F65. 相似文献
19.
We prove limit theorems for row sums of a rowwise independent infinitesimal array of random variables with values in a locally compact Abelian group. First we give a proof of Gaiser's theorem [4, Satz 1.3.6], since it does not have an easy access and it is not complete. This theorem gives sufficient conditions for convergence of the row sums, but the limit measure cannot have a nondegenerate idempotent factor. Then we prove necessary and sufficient conditions for convergence of the row sums, where the limit measure can be also a nondegenerate Haar measure on a compact subgroup. Finally, we investigate special cases: the torus group, the group of p ‐adic integers and the p ‐adic solenoid. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
In this paper we present a counterexample of compact domination compact operator T such that |T'| is compact but |T| need not compact. 相似文献