共查询到20条相似文献,搜索用时 31 毫秒
1.
Christopher Mouron 《Proceedings of the American Mathematical Society》2002,130(11):3409-3413
A homeomorphism is called expansive provided that for some fixed 0$"> and every there exists an integer , dependent only on and , such that c$">. It is shown that if is a tree-like continuum, then cannot be expansive.
2.
John R. Akeroyd 《Proceedings of the American Mathematical Society》2002,130(11):3349-3354
Let be a finite, positive Borel measure with support in such that - the closure of the polynomials in - is irreducible and each point in is a bounded point evaluation for . We show that if 0$">and there is a nontrivial subarc of such that
then for each nontrivial closed invariant subspace for the shift on .
-\infty,\end{displaymath}">
then for each nontrivial closed invariant subspace for the shift on .
3.
Akira Koyama Manuel A. Moron 《Proceedings of the American Mathematical Society》2002,130(10):3091-3096
We shall prove the following: Let be a refinable map between paracompact spaces. Then is finitistic if and only if is finitistic. Let be a hereditary shape equivalence between metric spaces. Then if is finitistic, is finitistic.
4.
Ian M. Musson 《Proceedings of the American Mathematical Society》2002,130(11):3185-3191
Let be a classical simple Lie superalgebra. We describe the prime ideals in the enveloping algebra such that satisfies a polynomial identity. If the factor algebra is not artinian, then it is an order in a matrix algebra over . 相似文献
5.
Jö rg Eschmeier Roland Wolff 《Proceedings of the American Mathematical Society》2002,130(1):95-102
Suppose that is an inner map and that . We show that the identity
holds with an abstract boundary value . If the natural compatibility condition is satisfied, then . Here, denotes the image of the surface measure on under . In particular, is inner if and are inner and . Furthermore, we characterize the boundedness of composition operators on Hardy spaces in terms of the absolute continuity of .
6.
Benjamin D. Miller Christian Rosendal 《Proceedings of the American Mathematical Society》2007,135(2):517-522
Suppose that and are Polish groups which act in a Borel fashion on Polish spaces and . Let and denote the corresponding orbit equivalence relations, and and the corresponding Borel full groups. Modulo the obvious counterexamples, we show that .
7.
Ryszard Rudnicki 《Proceedings of the American Mathematical Society》2002,130(7):1981-1982
We prove that the local lower and upper pointwise dimensions of a probability measure are bounded from below by the lower generalized dimension for 1$">and from above by the upper generalized dimension for .
8.
Wieslaw Kubis 《Proceedings of the American Mathematical Society》2003,131(2):619-623
A coloring of a set is any subset of , where 1$"> is a natural number. We give some sufficient conditions for the existence of a perfect -homogeneous set, in the case where is and is a Polish space. In particular, we show that it is sufficient that there exist -homogeneous sets of arbitrarily large countable Cantor-Bendixson rank. We apply our methods to show that an analytic subset of the plane contains a perfect -clique if it contains any uncountable -clique, where is a natural number or (a set is a -clique in if the convex hull of any of its -element subsets is not contained in ).
9.
Edward Formanek 《Proceedings of the American Mathematical Society》2002,130(4):935-937
Let be a free group of finite rank , let be the semigroup of endomorphisms of , and let be the group of automorphisms of .
Theorem. If is an automorphism of , then there is an such that for all .
10.
Thomas Schlumprecht Vladimir G. Troitsky 《Proceedings of the American Mathematical Society》2003,131(5):1405-1413
We show that C. J. Read's example of an operator on which does not have any non-trivial invariant subspaces is not the adjoint of an operator on a predual of . Furthermore, we present a bounded diagonal operator such that even though is unbounded, the operator is a bounded operator on with invariant subspaces, and is adjoint to an operator on .
11.
Let denote the (upper) unitriangular group of degree over the finite field with elements. In this paper we consider the basic (complex) characters of and we prove that every irreducible (complex) character of is a constituent of a unique basic character. This result extends a previous result which was proved by the author under the assumption , where is the characteristic of the field .
12.
Stephen J. Gardiner Mary Hanley 《Proceedings of the American Mathematical Society》2003,131(3):773-779
Let denote a relatively closed subset of the unit ball of . The purpose of this paper is to characterize those sets which have the following property: any harmonic function on which satisfies on (where 0$">) can be locally uniformly approximated on by a sequence of harmonic polynomials which satisfy the same inequality on . This answers a question posed by Stray, who had earlier solved the corresponding problem for holomorphic functions on the unit disc.
13.
Damir Bakic 《Proceedings of the American Mathematical Society》2005,133(2):441-448
We prove the following generalization of the noncommutative Tietze extension theorem: if is a countably generated Hilbert -module over a -unital -algebra, then the canonical extension of a surjective morphism of Hilbert -modules to extended (multiplier) modules, , is also surjective.
14.
Kohzo Yamada 《Proceedings of the American Mathematical Society》2002,130(8):2461-2469
Let and be respectively the free topological group and the free Abelian topological group on a Tychonoff space . For every natural number we denote by () the subset of () consisting of all words of reduced length . It is well known that if a space is not discrete, then neither nor is Fréchet-Urysohn, and hence first countable. On the other hand, it is seen that both and are Fréchet-Urysohn for a paracompact Fréchet-Urysohn space . In this paper, we prove first that for a metrizable space , () is Fréchet-Urysohn if and only if the set of all non-isolated points of is compact and is Fréchet-Urysohn if and only if is compact or discrete. As applications, we characterize the metrizable space such that is Fréchet-Urysohn for each and is Fréchet-Urysohn for each except for . In addition, however, there is a first countable, and hence Fréchet-Urysohn subspace of () which is not contained in any (). We shall show that if such a space is first countable, then it has a special form in (). On the other hand, we give an example showing that if the space is Fréchet-Urysohn, then it need not have the form.
15.
Marek Lassak 《Proceedings of the American Mathematical Society》2002,130(10):3075-3084
Let be an arbitrary planar convex body. We prove that contains an axially symmetric convex body of area at least . Also approximation by some specific axially symmetric bodies is considered. In particular, we can inscribe a rhombus of area at least in , and we can circumscribe a homothetic rhombus of area at most about . The homothety ratio is at most . Those factors and , as well as the ratio , cannot be improved.
16.
Vladimir G. Troitsky 《Proceedings of the American Mathematical Society》2000,128(2):521-525
We show that the celebrated Lomonosov theorem cannot be improved by increasing the number of commuting operators. Specifically, we prove that if is the operator without a non-trivial closed invariant subspace constructed by C. J. Read, then there are three operators , and (non-multiples of the identity) such that commutes with , commutes with , commutes with , and is compact. It is also shown that the commutant of contains only series of .
17.
Open covers and partition relations 总被引:1,自引:0,他引:1
Marion Scheepers 《Proceedings of the American Mathematical Society》1999,127(2):577-581
An open cover of a topological space is said to be an -cover if there is for each finite subset of the space a member of the cover which contains the finite set, but the space itself is not a member of the cover. We prove theorems which imply that a set of real numbers has Rothberger's property if, and only if, for each positive integer , for each -cover of , and for each function from the two-element subsets of , there is a subset of such that is constant on , and each element of belongs to infinitely many elements of (Theorem 1). A similar characterization is given of Menger's property for sets of real numbers (Theorem 6).
18.
Young Min Han Slavisa V. Djordjevic 《Proceedings of the American Mathematical Society》2002,130(3):715-722
If is a upper triangular matrix on the Hilbert space , then -Weyl's theorem for and need not imply -Weyl's theorem for , even when . In this note we explore how -Weyl's theorem and -Browder's theorem survive for operator matrices on the Hilbert space.
19.
Ljiljana Arambasic 《Proceedings of the American Mathematical Society》2007,135(2):469-478
Let be a countably generated Hilbert -module over a -algebra We prove that a sequence is a standard frame for if and only if the sum converges in norm for every and if there are constants such that for every We also prove that surjective adjointable operators preserve standard frames. A class of frames for countably generated Hilbert -modules over the -algebra of all compact operators on some Hilbert space is discussed.
20.
Paolo Lipparini 《Proceedings of the American Mathematical Society》2000,128(2):605-609
We prove the following: Theorem A. If is a -regular ultrafilter, then either
- (a)
- is -regular, or
- (b)
- the cofinality of the linear order is , and is -regular for all .