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51.
Gromoll and Meyer have represented a certain exotic 7-sphere as a biquotient of the Lie group . We show for a 2-parameter family of left invariant metrics on that the induced metric on has strictly positive sectional curvature at all points outside four subvarieties of codimension which we describe explicitly.
52.
Aleksandar Ivić 《Central European Journal of Mathematics》2005,3(2):203-214
Let Δ(x) denote the error term in the Dirichlet divisor problem, and E(T) the error term in the asymptotic formula for the mean square of
. If E
*(t)=E(t)-2πΔ*(t/2π) with
, then we obtain
and
It is also shown how bounds for moments of | E
*(t)| lead to bounds for moments of
. 相似文献
53.
Let S be topological semigroup, we consider an appropriate semigroup compactification of S. In this paper we study the connection between subgroups of a maximal group in a minimal left ideal of , which arise as equivalence classes of some closed left congruence, and the minimal ow characterized by the left congruence. A particular topology is defined on a maximal group and it is shown that a closed subgroup under this topology is precisely the intersection of an equivalence class with the maximal group for some left congruence on . 相似文献
54.
D. V. Osin 《Functional Analysis and Its Applications》2002,36(4):290-297
Let H be an infinite hyperbolic group with Kazhdan property (T) and let (H,X) denote the Kazhdan constant of H with respect to a generating set X. We prove that infX(H,X)=0, where the infimum is taken over all finite generating sets of H. In particular, this gives an answer to a Lubotzky question. 相似文献
55.
Belmesnaoui Aqzzouz 《Applied Categorical Structures》2002,10(6):603-616
We define the -product of a -space by a quotient Banach space. We give conditions under which this -product will be monic. Finally, we define the
c
-product of a Schwartz b-space by a quotient Banach space and we give some examples of applications. 相似文献
56.
Charalambos Charitos Georgios Tsapogas 《Transactions of the American Mathematical Society》2002,354(1):235-264
If is a proper -space and a non-elementary discrete group of isometries acting properly discontinuously on it is shown that the geodesic flow on the quotient space is topologically mixing, provided that the generalized Busemann function has zeros on the boundary and the non-wandering set of the flow equals the whole quotient space of geodesics (the latter being redundant when is compact). Applications include the proof of topological mixing for (A) compact negatively curved polyhedra, (B) compact quotients of proper geodesically complete -spaces by a one-ended group of isometries and (C) finite -dimensional ideal polyhedra.
57.
Zhiguo Hu 《Proceedings of the American Mathematical Society》2000,128(8):2473-2478
Let be a locally compact group and let denote the -algebra generated by left translation operators on . Let and be the spaces of almost periodic and weakly almost periodic functionals on the Fourier algebra , respectively. It is shown that if contains an open abelian subgroup, then (1) if and only if is norm dense in ; (2) is a -algebra if is norm dense in , where denotes the set of elements in with compact support. In particular, for any amenable locally compact group which contains an open abelian subgroup, has the dual Bohr approximation property and is a -algebra.
58.
集合H上矩阵A的左(右)逆、伪左(右)逆 总被引:1,自引:0,他引:1
王俊青 《数学的实践与认识》2000,30(3):376-379
以集合 S与空集Φ的交、并运算为背景 ,定义集合 H ={ 0 ,1 }中的加法与乘法运算 0 ,并考虑 H上一个 s×n级矩阵的左逆矩阵、右逆矩阵以及伪左逆矩阵、伪右逆矩阵的定义 ,并且证明了矩阵 A有左、右逆矩阵 ,A有伪左、右逆矩阵的充分必要条件 . 相似文献
59.
60.
M. Filali 《Proceedings of the American Mathematical Society》1999,127(8):2325-2333
Let be a locally compact group, let be its group algebra, let be its usual measure algebra, let be the second dual of with an Arens product, and let be the conjugate of the space of bounded, left uniformly continuous, complex-valued functions on with an Arens-type product. We find all the finite-dimensional left ideals of these algebras. We deduce that such ideals exist in and if and only if is compact, and in (except those generated by right annihilators of ) and if and only if is amenable.