共查询到20条相似文献,搜索用时 15 毫秒
1.
Narutaka Ozawa 《Proceedings of the American Mathematical Society》2004,132(2):487-490
Gromov constructed uncountably many pairwise nonisomorphic discrete groups with Kazhdan's property . We will show that no separable -factor can contain all these groups in its unitary group. In particular, no separable -factor can contain all separable -factors in it. We also show that the full group -algebras of some of these groups fail the lifting property.
2.
Danny Calegari Nathan M. Dunfield 《Proceedings of the American Mathematical Society》2006,134(11):3131-3136
We give an example of a subgroup of which is a strictly ascending HNN extension of a non-abelian finitely generated free group . In particular, we exhibit a free group in of rank which is conjugate to a proper subgroup of itself. This answers positively a question of Drutu and Sapir (2005). The main ingredient in our construction is a specific finite volume (non-compact) hyperbolic 3-manifold which is a surface bundle over the circle. In particular, most of comes from the fundamental group of a surface fiber. A key feature of is that there is an element of in with an eigenvalue which is the square root of a rational integer. We also use the Bass-Serre tree of a field with a discrete valuation to show that the group we construct is actually free.
3.
Semi-finite forms of bilateral basic hypergeometric series 总被引:1,自引:0,他引:1
William Y. C. Chen Amy M. Fu 《Proceedings of the American Mathematical Society》2006,134(6):1719-1725
We show that several classical bilateral summation and transformation formulas have semi-finite forms. We obtain these semi-finite forms from unilateral summation and transformation formulas. Our method can be applied to derive Ramanujan's summation, Bailey's transformations, and Bailey's summation.
4.
Jon P. Bannon 《Proceedings of the American Mathematical Society》2005,133(3):835-840
We introduce a notion of transitive family of subspaces relative to a type factor, and hence a notion of transitive family of projections in such a factor. We show that whenever is a factor of type and is generated by two self-adjoint elements, then contains a transitive family of projections. Finally, we exhibit a free transitive family of projections that generate a factor of type .
5.
Masahiro Shioya 《Proceedings of the American Mathematical Society》2006,134(6):1819-1821
Let be a -supercompact cardinal. We show that carries a normal ultrafilter with a property introduced by Menas. With it we give a transparent proof of Kamo's theorem that carries a normal ultrafilter with the partition property.
6.
We consider efficient methods for the recovery of block sparse signals from underdetermined system of linear equations. We show that if the measurement matrix satisfies the block RIP with δ2s 0.4931, then every block s-sparse signal can be recovered through the proposed mixed l2 /l1 -minimization approach in the noiseless case and is stably recovered in the presence of noise and mismodeling error. This improves the result of Eldar and Mishali (in IEEE Trans. Inform. Theory 55: 5302-5316, 2009). We also give another sufficient condition on block RIP for such recovery method: δs 0.307. 相似文献
7.
Antonio Aizpuru Francisco Javier Garcia-Pacheco 《Proceedings of the American Mathematical Society》2006,134(7):2109-2115
The aim of this paper is to study the set of all -summand vectors of a real Banach space . We provide a characterization of -summand vectors in smooth real Banach spaces and a general decomposition theorem which shows that every real Banach space can be decomposed as an -sum of a Hilbert space and a Banach space without nontrivial -summand vectors. As a consequence, we generalize some results and we obtain intrinsic characterizations of real Hilbert spaces.
8.
Eduardo Gonzalez 《Transactions of the American Mathematical Society》2006,358(7):2927-2948
This paper studies symplectic manifolds that admit semi-free circle actions with isolated fixed points. We prove, using results on the Seidel element, that the (small) quantum cohomology of a -dimensional manifold of this type is isomorphic to the (small) quantum cohomology of a product of copies of . This generalizes a result due to Tolman and Weitsman.
9.
Suppose that is a smooth -action on a closed smooth -dimensional manifold such that all Stiefel-Whitney classes of the tangent bundle to each connected component of the fixed point set vanish in positive dimension. This paper shows that if 2^k\dim F$"> and each -dimensional part possesses the linear independence property, then bounds equivariantly, and in particular, is the best possible upper bound of if is nonbounding.
10.
Georgia Benkart Paul Terwilliger 《Proceedings of the American Mathematical Society》2007,135(6):1659-1668
We consider the three-point loop algebra, where denotes a field of characteristic 0 and is an indeterminate. The universal central extension of was determined by Bremner. In this note, we give a presentation for via generators and relations, which highlights a certain symmetry over the alternating group . To obtain our presentation of , we use the realization of as the tetrahedron Lie algebra.
11.
Yaling Li & Wengu Chen 《计算数学(英文版)》2019,37(1):61-75
In this paper, we consider the recovery of block sparse signals, whose nonzero entries
appear in blocks (or clusters) rather than spread arbitrarily throughout the signal, from
incomplete linear measurements. A high order sufficient condition based on block RIP
is obtained to guarantee the stable recovery of all block sparse signals in the presence
of noise, and robust recovery when signals are not exactly block sparse via mixed $l_2/l_1$ minimization. Moreover, a concrete example is established to ensure the condition is
sharp. The significance of the results presented in this paper lies in the fact that recovery
may be possible under more general conditions by exploiting the block structure of the
sparsity pattern instead of the conventional sparsity pattern. 相似文献
12.
Shutao Chen Yunan Cui Henryk Hudzik 《Proceedings of the American Mathematical Society》2004,132(2):473-480
Criteria in order that an Orlicz space equipped with the Orlicz norm contains a linearly isometric copy (or an order linearly isometric copy) of (or ) are given.
13.
14.
Qin Hourong 《数学年刊B辑(英文版)》1996,17(1):63-72
The author shows that K2Z[1+(-35的平根号)/2 ]?A ≈Z/2Z. The method of proof is a generalization of the Tate‘s method. 相似文献
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16.
In this paper, we classify all optimal linear[n, n/2] codes up to length 12. We show that thereis a unique optimal [10, 5, 5] code up to equivalence. 相似文献
17.
This paper concerns the rate of -concentration of the blow-up solutions for the critical nonlinear Schrödinger equation. The result of Tsutsumi is improved in terms of Merle and Raphaël's recent arguments.
18.
An L(d0,d2,...,dt)-labeling of a graph G is a function f from its vertex set V(G) to the set {0,1,..., k} for some positive integer k such that If(x) - f(y)l ≥di, if the distance between vertices x and y in G is equal to i for i = 1,2,...,t. The L(d1,d2,...,dt)-number λ(G;d1,d2,... ,dt) of G is the smallest integer number k such that G has an L(d1,d2,...,dr)- labeling with max{f (x)|x ∈ V(G)} = k. In this paper, we obtain the exact values for λ(Cn; 2, 2, 1) and λ(Cn; 3, 2, 1), and present lower and upper bounds for λ(Cn; 2,..., 2, 1,..., 1) 相似文献
19.
For a word w in an alphabet Γ, the alternation word digraph Alt(w), a certain directed acyclic graph associated with w, is presented as a means to analyze the free spectrum of the Perkins monoid \(\mathbf{B_2^1}\). Let \((f_n^{\mathbf{B_2^1}})\) denote the free spectrum of \(\mathbf{B_2^1}\), let a n be the number of distinct alternation word digraphs on words whose alphabet is contained in {x 1,..., x n }, and let p n denote the number of distinct labeled posets on {1,..., n}. The word problem for the Perkins semigroup \(\mathbf{B_2^1}\) is solved here in terms of alternation word digraphs: Roughly speaking, two words u and v are equivalent over \(\mathbf{B_2^1}\) if and only if certain alternation graphs associated with u and v are equal. This solution provides the main application, the bounds: \(p_n \leq a_n \leq f_n^{\mathbf{B_2^1}} \leq 2^{n}a_{2n}^2\). A result of the second author in a companion paper states that \((\operatorname{log} \; a_n)\in O(n^3)\), from which it follows that \((\operatorname{log} f_n^{\mathbf{B_2^1}})\in O(n^3)\) as well. Alternation word digraphs are of independent interest combinatorially. It is shown here that the computational complexity problem that has as instance {u,v} where u,v are words of finite length, and question “Is Alt(u)?=?Alt(v)?”, is co-NP-complete. Additionally, alternation word digraphs are acyclic, and certain of them are natural extensions of posets; each realizer of a finite poset determines an extension by an alternation word digraph. 相似文献
20.
Let \({\mathcal L}\equiv-\Delta+V\) be the Schrödinger operator in \({{\mathbb R}^n}\), where V is a nonnegative function satisfying the reverse Hölder inequality. Let ρ be an admissible function modeled on the known auxiliary function determined by V. In this paper, the authors characterize the localized Hardy spaces \(H^1_\rho({{\mathbb R}^n})\) in terms of localized Riesz transforms and establish the boundedness on the BMO-type space \({\mathop\mathrm{BMO_\rho({\mathbb R}^n)}}\) of these operators as well as the boundedness from \({\mathop\mathrm{BMO_\rho({\mathbb R}^n)}}\) to \({\mathop\mathrm{BLO_\rho({\mathbb R}^n)}}\) of their corresponding maximal operators, and as a consequence, the authors obtain the Fefferman–Stein decomposition of \({\mathop\mathrm{BMO_\rho({\mathbb R}^n)}}\) via localized Riesz transforms. When ρ is the known auxiliary function determined by V, \({\mathop\mathrm{BMO_\rho({\mathbb R}^n)}}\) is just the known space \(\mathop\mathrm{BMO}_{\mathcal L}({{\mathbb R}^n})\), and \({\mathop\mathrm{BLO_\rho({\mathbb R}^n)}}\) in this case is correspondingly denoted by \(\mathop\mathrm{BLO}_{\mathcal L}({{\mathbb R}^n})\). As applications, when n?≥?3, the authors further obtain the boundedness on \(\mathop\mathrm{BMO}_{\mathcal L}({{\mathbb R}^n})\) of Riesz transforms \(\nabla{\mathcal L}^{-1/2}\) and their adjoint operators, as well as the boundedness from \(\mathop\mathrm{BMO}_{\mathcal L}({{\mathbb R}^n})\) to \(\mathop\mathrm{BLO}_{\mathcal L}({{\mathbb R}^n})\) of their maximal operators. Also, some endpoint estimates of fractional integrals associated to \({\mathcal L}\) are presented. 相似文献