共查询到20条相似文献,搜索用时 15 毫秒
1.
T. S. Quek 《Proceedings of the American Mathematical Society》1999,127(8):2343-2351
In his 1986 paper in the Rev. Mat. Iberoamericana, A. Carbery proved that a singular integral operator is of weak type on if its lacunary pieces satisfy a certain regularity condition. In this paper we prove that Carbery's result is sharp in a certain sense. We also obtain a weighted analogue of Carbery's result. Some applications of our results are also given.
2.
Marco Bramanti Luca Brandolini 《Transactions of the American Mathematical Society》2000,352(2):781-822
Let be a system of real smooth vector fields, satisfying Hörmander's condition in some bounded domain (). We consider the differential operator
where the coefficients are real valued, bounded measurable functions, satisfying the uniform ellipticity condition:
for a.e. , every , some constant . Moreover, we assume that the coefficients belong to the space VMO (``Vanishing Mean Oscillation'), defined with respect to the subelliptic metric induced by the vector fields . We prove the following local -estimate:
for every , . We also prove the local Hölder continuity for solutions to for any with large enough. Finally, we prove -estimates for higher order derivatives of , whenever and the coefficients are more regular.
3.
Kevin A. Roper Ted J. Suffridge 《Transactions of the American Mathematical Society》1999,351(5):1803-1833
Not many convex mappings on the unit ball in for are known. We introduce two families of mappings, which we believe are actually identical, that both contain the convex mappings. These families which we have named the ``Quasi-Convex Mappings, Types A and B' seem to be natural generalizations of the convex mappings in the plane. It is much easier to check whether a function is in one of these classes than to check for convexity. We show that the upper and lower bounds on the growth rate of such mappings is the same as for the convex mappings.
4.
Mingliang Cai 《Proceedings of the American Mathematical Society》1999,127(2):569-575
We prove some integral inequalities for immersed tori in the three sphere. The functionals considered are generalizations of the Willmore functional.
5.
Christopher Hoffman 《Transactions of the American Mathematical Society》1999,351(10):4263-4280
We present a general method for constructing families of measure preserving transformations which are and loosely Bernoulli with various ergodic theoretical properties. For example, we construct two transformations which are weakly isomorphic but not isomorphic, and a transformation with no roots. Ornstein's isomorphism theorem says families of Bernoulli shifts cannot have these properties. The construction uses a combination of properties from maps constructed by Ornstein and Shields, and Rudolph, and reduces the question of isomorphism of two transformations to the conjugacy of two related permutations.
6.
Y. Bahturin A. Giambruno M. Zaicev 《Proceedings of the American Mathematical Society》1999,127(1):63-69
Let be an algebra over a field and a finite group of automorphisms and anti-automorphisms of . We prove that if satisfies an essential -polynomial identity of degree , then the -codimensions of are exponentially bounded and satisfies a polynomial identity whose degree is bounded by an explicit function of . As a consequence we show that if is an algebra with involution satisfying a -polynomial identity of degree , then the -codimensions of are exponentially bounded; this gives a new proof of a theorem of Amitsur stating that in this case must satisfy a polynomial identity and we can now give an upper bound on the degree of this identity.
7.
N. P. Strickland 《Transactions of the American Mathematical Society》1999,351(7):2569-2606
Elmendorf, Kriz, Mandell and May have used their technology of modules over highly structured ring spectra to give new constructions of -modules such as , and so on, which makes it much easier to analyse product structures on these spectra. Unfortunately, their construction only works in its simplest form for modules over that are concentrated in degrees divisible by ; this guarantees that various obstruction groups are trivial. We extend these results to the cases where or the homotopy groups are allowed to be nonzero in all even degrees; in this context the obstruction groups are nontrivial. We shall show that there are never any obstructions to associativity, and that the obstructions to commutativity are given by a certain power operation; this was inspired by parallel results of Mironov in Baas-Sullivan theory. We use formal group theory to derive various formulae for this power operation, and deduce a number of results about realising -local -modules as -modules.
8.
9.
Juraj Simko 《Proceedings of the American Mathematical Society》1999,127(2):323-325
It is proved that the theory of the class of all betweenness spaces metrizable by real-valued metrics does not coincide with the theory of the class of all betweenness spaces metrizable by metrics taking values in any ordered field. This solves a problem raised by Mendris and Zlatov{s}.
10.
William S. Cohn 《Proceedings of the American Mathematical Society》1999,127(2):509-517
We show that a function is the derivative of a function in the Hardy space of the unit disk for if and only if where and . Here, can be chosen to be non-vanishing, , and . As an application, we characterize positive measures on the unit disk such that the operator is bounded from the tent space to , where .
11.
Anthony Bahri Martin Bendersky 《Transactions of the American Mathematical Society》2000,352(3):1191-1202
Toric manifolds, a topological generalization of smooth projective toric varieties, are determined by an -dimensional simple convex polytope and a function from the set of codimension-one faces into the primitive vectors of an integer lattice. Their cohomology was determined by Davis and Januszkiewicz in 1991 and corresponds with the theorem of Danilov-Jurkiewicz in the toric variety case. Recently it has been shown by Buchstaber and Ray that they generate the complex cobordism ring. We use the Adams spectral sequence to compute the -theory of all toric manifolds and certain singular toric varieties.
12.
Jen-Tseh Chang James W. Cogdell 《Proceedings of the American Mathematical Society》1999,127(4):1251-1256
We compute the -homology for a class of representations of
and which admit a Whittaker model. They are all completely reducible.
and which admit a Whittaker model. They are all completely reducible.
13.
Neal J. Fowler Marcelo Laca Iain Raeburn 《Proceedings of the American Mathematical Society》2000,128(8):2319-2327
We associate -algebras to infinite directed graphs that are not necessarily locally finite. By realizing these algebras as Cuntz-Krieger algebras in the sense of Exel and Laca, we are able to give criteria for their uniqueness and simplicity, generalizing results of Kumjian, Pask, Raeburn, and Renault for locally finite directed graphs.
14.
Kensho Takegoshi 《Proceedings of the American Mathematical Society》1998,126(12):3749-3753
We show a maximum principle for -harmonic maps with -finite energy. As an application we can generalize a non-existence theorem for harmonic maps with finite Dirichlet integral by Schoen and Yau to those maps.
15.
L. Rodrí guez-Piazza M. C. Romero-Moreno 《Transactions of the American Mathematical Society》2000,352(1):379-395
Let be a real number such that and its conjugate exponent . We prove that for an operator defined on with values in a Banach space, the image of the unit ball determines whether belongs to any operator ideal and its operator ideal norm. We also show that this result fails to be true in the remaining cases of . Finally we prove that when the result holds in finite dimension, the map which associates to the image of the unit ball the operator ideal norm is continuous with respect to the Hausdorff metric.
16.
Byeong-Kweon Oh 《Proceedings of the American Mathematical Society》2000,128(3):683-689
Let be the minimal rank of -universal -lattices, by which we mean positive definite -lattices which represent all positive -lattices of rank . It is a well known fact that for . In this paper, we determine and find all -universal lattices of rank for .
17.
Robert Lauter 《Proceedings of the American Mathematical Society》2000,128(7):1955-1961
We compute the length of the -algebra generated by the algebra of b-pseudodifferential operators of order on compact manifolds with corners.
18.
Suppose is a simple reductive -adic group with Weyl group . We give a classification of the irreducible representations of which can be extended to real hermitian representations of the associated graded Hecke algebra . Such representations correspond to unitary representations of which have a small spectrum when restricted to an Iwahori subgroup.
19.
An endpoint boundedness result is established for a class of oscillatory integral operators.
20.
Diane Benjamin 《Proceedings of the American Mathematical Society》1999,127(2):371-376
Let denote the largest irreducible character degree of a finite group , and let be a prime. Two results are obtained. First, we show that, if is a -solvable group and if , then . Next, we restrict attention to solvable groups and show that, if and if is a Sylow -subgroup of , then .