鞅变换与可预报Orlicz-Hardy鞅空间

以鞅变换为工具,刻画了由凹函数所定义的可预报Orlicz-Hardy鞅空间之间的相互关系.用构造性的方法证明了:当Φ_1为凹函数且Φ_1■Φ_2时,鞅f∈P_(Φ_1),当且仅当f是P_(Φ_2)中某个鞅g的鞅变换.所得结果推广了Garsia早年的一个经典结论.     

LΦ可料控制鞅Hardy-Orlicz空间之间的鞅变换

以鞅变换为工具,刻画了LΦ可料控制鞅的Hardy-Orlicz空间之间的相互关系,设Φ1和Φ2是两个Young函数,并在某种意义上Φ2强于Φ1(具体定义见正文),以构造性的方法证明了Hardy-Orlicz空间(D)Φ1中的鞅恰好是Hardy-Orlicz空间(D)Φ2中的鞅的鞅变换.所得的结果推广了已有文献中的相关结论.     

Hilbert空间的一个特征性质

在实值鞅空间中成立的凸Φ函数不等式 EΦ(M~(2)(f))≤CEΦ(m~((2))(f), (1)(见[2],§4.2定理4,符号意义见后)对于取值于Banach空间的鞅一般不再成立.当X具备何种条件时,在其中取值的每个鞅满足(1)式?本文将证明,x必须并且只须同构于Hilbert空间. 设(Ω,Σ,Ρ)是概率空间,(?)是Σ的递增子σ代数族,与(?)适应的鞅记为f=(f_(n)),     

L~Φ可料控制鞅Hardy-Orlicz空间之间的鞅变换

以鞅变换为工具,刻画了L^Φ可料控制鞅的Hardy-Orlicz空间之间的相互关系,设Φ₁和Φ₂是两个Young函数,并在某种意义上Φ₂强于Φ1（具体定义见正文）,以构造性的方法证明了Hardy-Orlicz空间D_Φ1中的鞅恰好是Hardy-Orlicz空间D_Φ2中的鞅的鞅变换.所得的结果推广了已有文献中的相关结论.     

鞅不等式与 Banach 空间的凸性和光滑性

我们用 B 值鞅的 P 方函数 S~(p)f 的 a.e.有限性刻划了 Banach 空间的p 一致可凸性质,建立了这种函数的凸Φ函数不等式,讨论了这些不等式成立的条件,鞅变换的性质以及鞅的局部收敛性与 Banach 空间的 q一致凸性和 p一致光滑性的关系,同时给出了超自反空间以及与 Hilbert 空间同构的 Banach空间的特征.     

B-值鞅Hardy空间与BMO空间的实内插

研究了B值鞅Hardy空间与BMO空间的实内插，并利用所得结果，讨论了鞅Hardy空间的内插空间的共轭问题。     

Hardy-Orlicz-amalgam鞅空间的原子分解

引入了Hardy-Orlicz-amalgam鞅空间,当Φ为凹函数且0 Φ≤q_Φ≤q≤1时,建立了Hardy-Orlicz-amalgam鞅空间H₍(Φ,q))^s的原子分解定理.作为应用,以此为工具给出了其共轭空间的刻画.     

拟鞅变换与UMD空间

本文定义了拟鞅变换,将Burkholder关于变换的不等式推广到拟鞅,同时应用拟鞅变换的若干性质刻划了UMD空间的特征.     

BMO鞅空间上极大算子与均方算子的有界性

本文证明了,q 均方算子在 X 值 BMO 鞅空间上是有界的当且仅当 X 同构于 q凸 Banach 空间。此外给出了极大算子与 q 均方算子的 BMO 范数,讨论了鞅空间(?)_q 与BMO_q 的相互包含关系并以此刻划了 Banach 空间的几何性质。     

弱Orlicz鞅空间的极大不等式

本文研究了弱Orlicz鞅空间的双Φ-不等式．利用鞅的极大算子理论和弱Orlicz范数的特点,得到了弱Orlicz鞅空间极大算子的Doob不等式和强弱(Φ1,Φ2)-型不等式．     

鞅的双权双&Phi|-函数极大不等式

该文研究了鞅Orlicz空间加权不等式, 主要包括弱(Φ₁,Φ₂) -型加权不等式和强(Φ₁,Φ₂) -型加权不等式. 讨论了这些不等式成立的充分必要条件.     

函数域的K_2群的挠元

设F是域,令G_n(F)={{a,φ_n(a)}∈K_2(F)| a,Φ_n(a)∈F~*},这里Φ_n(x)是n次分圆多项式.使用函数域的ABC定理证明了若F是常数域为k函数域,l≠ch(k)是素数,则对n≥3且l>2或n>3且l=2,G_(ln)(F)不是K_2(F)的子群.由此部分地证实了Browkin的猜想.     

On the arithmetic of tame monoids with applications to Krull monoids and Mori domains

Let H be an atomic monoid (e.g., the multiplicative monoid of a noetherian domain). For an element b∈H, let ω(H,b) be the smallest  N∈N₀∪{∞} having the following property: if  n∈N and  a₁,…,a_n∈H are such that b divides  a₁⋅…⋅a_n, then b already divides a subproduct of a₁⋅…⋅a_n consisting of at most N factors. The monoid H is called tame if . This is a well-studied property in factorization theory, and for various classes of domains there are explicit criteria for being tame. In the present paper, we show that, for a large class of Krull monoids (including all Krull domains), the monoid is tame if and only if the associated Davenport constant is finite. Furthermore, we show that tame monoids satisfy the Structure Theorem for Sets of Lengths. That is, we prove that in a tame monoid there is a constant M such that the set of lengths of any element is an almost arithmetical multiprogression with bound M.     

On functions in p-adic BMO and the distribution of prime integers

We study the spaces BMOp of functions of bounded mean oscillation modeled on a p-adic martingale, and determine their relationship with the ordinary, continuous space BMO of functions of bounded mean oscillation. Somewhat surprisingly, these results are related to information about the distribution of primes.     

Continuity properties in non-commutative convolution algebras, with applications in pseudo-differential calculus

We study continuity properties for a family {s_p}_p?1 of increasing Banach algebras under the twisted convolution, which also satisfies that a∈s_p, if and only if the Weyl operator a^w(x,D) is a Schatten-von Neumann operator of order p on L². We discuss inclusion relations between the s_p-spaces, Besov spaces and Sobolev spaces. We prove also a Young type result on s_p for dilated convolution. As an application we prove that f(a)∈s₁, when a∈s₁ and f is an entire odd function. We finally apply the results on Toeplitz operators and prove that we may extend the definition for such operators.     

Almost everywhere convergence of Banach space-valued Vilenkin-Fourier series

The duality between martingale Hardy and BMO spaces is generalized for Banach space valued martingales. It is proved that if X is a UMD Banach space and f ∈ L _p(X) for some 1 < p < ∞ then the Vilenkin-Fourier series of f converges to f almost everywhere in X norm, which is the extension of Carleson’s result. This paper was written while the author was researching at University of Vienna (NuHAG) supported by Lise Meitner fellowship No. M733-N04. This research was also supported by the Hungarian Scientific Research Funds (OTKA) No. T043769, T047128, T047132.     

J-子空间格代数上中心化子和广义导子的刻画

设L是Banach空间X上的J-子空间格,AlgL是相应的(J-子空间格代数.设φ:AlgL→AlgL是可加映射,对每个K∈(J)(L),dimK≥2.该文证明了下列表述等价:(1)φ是中心化子;(2)φ满足AB=0■φ(A)B=Aφ(B)=0;(3)φ满足AB+BA=0■φ(A)B+φ(B)A=Aφ(B)+Bφ(A)=0;(4)φ满足ABC+CBA=0■φ(A)BC+φ(C)BA=ABφ(C)+CBφ(A)=0.作为应用,得到AlgL上在零点广义可导的可加映射的完全刻画.     

Products of two involutions with prescribed eigenvalues and some applications

Let F be a field. In [Djokovic, Product of two involutions, Arch. Math. 18 (1967) 582-584] it was proved that a matrix A∈F^n×n can be written as A=BC, for some involutions B,C∈F^n×n, if and only if A is similar to A^-1. In this paper we describe the possible eigenvalues of the matrices B and C.As a consequence, in case charF≠2, we describe the possible similarity classes of (P₁₁⊕P₂₂)P^-1, when the nonsingular matrix P=[P_ij]∈F^n×n, i,j∈{1,2} and P₁₁∈F^s×s, varies.When F is an algebraically closed field and charF≠2, we also describe the possible similarity classes of [A_ij]∈F^n×n, i,j∈{1,2}, when A₁₁ and A₂₂ are square zero matrices and A₁₂ and A₂₁ vary.     

非交换Hp空间理论的若干进展——纪念李国平院士吴新谋教授诞辰100周年

该文分两部分综述非交换H_p 空间理论的研究背景、发展线路以及某些最新进展.第一部分介绍非交换Hardy 空间理论, 包括有限次对角代数的基本性质 (如唯一正规态开拓性质、分解性质、对数模性、不变子空间性质等),Szeg\"{o} 与Riesz 型分解定理和H¹-BMO 对偶定理等. 第二部分综述非交换 H_p鞅空间理论, 主要介绍各种非交换鞅不等式以及作者与合作者在非交换Hardy 鞅空间原子分解方面获得的最新结果. 该文还给出了非交换H_p空间理论有待解决的一些问题 和潜在的发展方向.