共查询到20条相似文献,搜索用时 15 毫秒
1.
We prove that the properties of acting metrically properly on some space with walls or some CAT(0) cube complex are closed
by taking the wreath product with . We also give a lower bound for the (equivariant) Hilbert space compression of in terms of the (equivariant) Hilbert space compression of H.
A la mémoire de Michel Matthey 相似文献
2.
Dennis Dreesen 《Journal of Functional Analysis》2011,261(12):3585-3611
We investigate the behavior of equivariant and non-equivariant Hilbert space compression under group constructions. Given the (equivariant or non-equivariant) Hilbert space compression of two groups, we find bounds on the compression of their free product. We also investigate the case of HNN-extensions of a group relative to a subgroup which is finite or of finite index. 相似文献
3.
Ruth Charney 《Geometriae Dedicata》2007,125(1):141-158
Recently, right-angled Artin groups have attracted much attention in geometric group theory. They have a rich structure of
subgroups and nice algorithmic properties, and they give rise to cubical complexes with a variety of applications. This survey
article is meant to introduce readers to these groups and to give an overview of the relevant literature.
相似文献
4.
Ghislain Jaudon 《Geometriae Dedicata》2008,135(1):23-27
By using the links between generalized roundness, negative type inequalities and equivariant Hilbert space compressions, we
obtain that the generalized roundness of the usual Cayley graph of finitely generated free groups and free abelian groups
of rank ≥ 2 equals 1. This answers a question of J-F. Lafont and S. Prassidis.
相似文献
5.
Piotr W. Nowak 《Journal of Functional Analysis》2007,243(1):323-344
We introduce a quasi-isometry invariant related to Property A and explore its connections to various other invariants of finitely generated groups. This allows to establish a direct relation between asymptotic dimension on one hand and isoperimetry and random walks on the other. We apply these results to reprove sharp estimates on isoperimetric profiles of some groups and to answer some questions in dimension theory. 相似文献
6.
Dudley Paul Johnson 《Stochastic Processes and their Applications》1985,19(1):183-187
We show that under mild conditions the joint densities Px1,…,xn) of the general discrete time stochastic process Xn on can be computed via where ? is in a Hilbert space , and T (x), x ? are linear operators on . We then show how the Central Limit Theorem can easily be derived from such representations. 相似文献
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In this paper, we first address the uniqueness of phaseless inverse discrete Hilbert transform (phaseless IDHT for short) from the magnitude of discrete Hilbert transform (DHT for short). The measurement vectors of phaseless IDHT do not satisfy the complement property, a traditional requirement for ensuring the uniqueness of phase retrieval. Consequently, the uniqueness problem of phaseless IDHT is essentially different from that of the traditional phase retrieval. For the phaseless IDHT related to compactly supported functions, conditions are given in our first main theorem to ensure the uniqueness. A condition on the step size of DHT is crucial for the insurance. The second main theorem concerns the uniqueness related to noncompactly supported functions. It is not the trivial generalization of the first main theorem. Our third main result is on the determination of signals in shift‐invariant spaces by phaseless IDHT. Note that the measurements used for the determination are the DHT magnitudes. They are the approximations to the Hilbert transform magnitudes. Recall that for the existing methods of phaseless sampling (a special phase‐retrieval problem), to determine a signal depends on the exact measurements but not the approximative ones. Therefore, our determination method is essentially different from the traditional phaseless sampling. Numerical simulations are conducted to examine the efficiency of phaseless IDHT and its application in determining signals in spline Hilbert shift‐invariant space. 相似文献
11.
E. A. Mirzakhanyan N. E. Mirzakhanyan 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2008,43(4):221-232
The paper discusses some equivalent ways of construction of infinite-dimensional homotopic groups of subsets and pairs of subsets in real Hilbert spaces. In the admissible class of K 0-continuous mappings, the homotopic invariance of the mentioned groups and their isomorphism are demonstrated in the case where the basic points belong to the same component of K 0-linear connectivity. 相似文献
12.
P. Chansangiam 《Journal of Mathematical Analysis and Applications》2009,356(2):525-276
Let B(H) be the space of all bounded linear operators on a complex separable Hilbert space H. Bohr inequality for Hilbert space operators asserts that for A,B∈B(H) and p,q>1 real numbers such that 1/p+1/q=1,
2|A+B|?p2|A|+q2|B| 相似文献
13.
D. W. Curtis 《Topology and its Applications》1985,20(3):201-221
We study properties of those σZ-sets in the Hilbert cube whose complements are homeomorphic to Hilbert space. A characterization of such sets is obtained in terms of a proximate local connectedness property and a dense imbedding condition. Some examples and applications are given, including the formulation of a tower condition useful for recognizing (f-d) cap sets. 相似文献
14.
A necessary and sufficient condition for exponential stability of Hilbert space contraction semigroups is obtained in terms
of an inequality involving the dissipative norm associated with the generator of the semigroup and with the Hilbert space
norm. 相似文献
15.
Sums of Hilbert space frames 总被引:1,自引:0,他引:1
Sofian Obeidat Peter G. Casazza Janet C. Tremain 《Journal of Mathematical Analysis and Applications》2009,351(2):579-585
We give simple necessary and sufficient conditions on Bessel sequences {fi} and {gi} and operators L1, L2 on a Hilbert space H so that {L1fi+L2gi} is a frame for H. This allows us to construct a large number of new Hilbert space frames from existing frames. 相似文献
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Masoumeh Faghih-Ahmadi Karim Hedayatian 《Journal of Mathematical Analysis and Applications》2022,505(2):125500
Let H be an infinite dimensional complex Hilbert space and T be a bounded linear operator on H. We show that if there exists such that the closure of is H, then there is a subsequence such that the closed linear span of is not the whole space H. 相似文献
18.
V. A. Koshcheev 《Mathematical Notes》2006,80(5-6):744-747
19.
Dimosthenis Drivaliaris 《Journal of Mathematical Analysis and Applications》2005,305(2):560-565
Let X be a real Banach space. We prove that the existence of an injective, positive, symmetric and not strictly singular operator from X into its dual implies that either X admits an equivalent Hilbertian norm or it contains a nontrivially complemented subspace which is isomorphic to a Hilbert space. We also treat the nonsymmetric case. 相似文献
20.
Zoltá n Sebestyé n Jan Stochel 《Proceedings of the American Mathematical Society》2005,133(6):1727-1731
A general factorization theorem for symmetrizable operators relating their spectra to spectra of selfadjoint operators induced by minimal factorizations is established. Its modified version essentially improves and completes a theorem of Jorgensen, which concerns diagonalizing operators with reflection symmetry.