Volterra Type Operators on Weighted Dirichlet*

The Carleson measures for weighted Dirichlet spaces had been characterized by Girela and Pel′aez, who also characterized the boundedness of Volterra type operators between weighted Dirichlet spaces. However, their characterizations for the boundedness are not complete. In this paper, the author completely characterizes the boundedness and compactness of Volterra type operators from the weighted Dirichlet spaces D^p_α to D^q_β (?1 < α, β and 0 < p < q < ∞), which essentially complete their works. Furthermore, the author investigates the order boundedness of Volterra type operators between weighted Dirichlet spaces.     

Weighted Composition Operators from α-Bloch Spaces to H^∞

The article not only presents the boundedness and compactness of the weighted composition operator from α-Bloch spaces（or little α-Bloch spaces） to H^∞, but also gives some estimates for the norm of the weighted composition operator.     

Products of Toeplitz and Hankel Operators on Fock-Sobolev Spaces

In this paper, the authors investigate the boundedness of Toeplitz product T_f T_g and Hankel product H^*_fH_g on Fock-Sobolev space for f, g ∈ P. As a result, the boundedness of Toeplitz operator T_f and Hankel operator H_g with f ∈ P is characterized.     

关于控制算子的若干注记

Let B(H) be the set of all bounded linear operators on a Hilbert space H. An operator T∈B(H) is called dominant if (T-λ)(T-λ)^*≤M_λ²(T-λ)^*(T-λ),?λ∈C.The numerical range of T is difined by W (T) = {(Tx, x): ‖x‖ = 1, x∈H}. In Section 1 some new characteristic of dominant operators are given. If C = AB - BA, we prove that O∈W(C)^- then A is a dominart or φ-quasihy ponor-mal. In Section 2 we prove that O∈σ_e(△_A^σ) if A is a dominant, where(?), we also prove that if A∈B(H) is a norm attaining Ф-quasihyponormal, then A has a non-trivial invariant subspace. In Section 3 we discuss the closeness of the range of bounded linear operator F_AB:X→AX-XB, and prove that R(δ_A)∩{A}′∩{Aⁿ}′=0, where δ_A:X→AX-XA.     

Boundedness of fractional integral operators on α-modulation spaces

In this paper, we obtain the boundedness of the fractional integral operators, the bilinear fractional integral operators and the bilinear Hilbert transform on α-modulation spaces.     

Positive Solutions for Asymptotically Linear Cone-Degenerate Elliptic Equations

In this paper, the authors study the asymptotically linear elliptic equation on manifold with conical singularities ??_Bu + λu = a(z)f(u), u ≥ 0 in R^N₊,where N = n + 1 ≥ 3, λ > 0, z = t,x₁,· · · ,x_n, and ?_B = (t?_t)^{2 + ?2_x1 + · · · + ?2_xn. Combining properties of cone-degenerate operator, the Pohozaev manifold and qualitative properties of the ground state solution for the limit equation, we obtain a positive solution under some suitable conditions on a and f.}     

TWO-DIMENSIONAL MAXIMAL OPERATOR OF DYADIC DERIVATIVE ON VILENKIN MARTINGALE SPACES

In [1] the boundedness of one dimensional maximal operator of dyadic derivative is discussed.In this paper,we consider the two-dimensional maximal operator of dyadic derivative on Vilenkin martingale spaces.With the help of counter-example we prove that the maximal operator is not bounded from the Hardy space H q to the Hardy space H q for 0相似文献   

变指标Herz-Morrey空间上的Marcinkiewicz积分算子高阶交换子

In the case of Ω∈ Lipγ(Sn-1)(0 γ≤ 1), we prove the boundedness of the Marcinkiewicz integral operator μΩon the variable exponent Herz-Morrey spaces. Also, we prove the boundedness of the higher order commutators μmΩ,bwith b ∈ BMO(Rn) on both variable exponent Herz spaces and Herz-Morrey spaces, and extend some known results.     

Heisenberg群上一类左不变LPDO的局部基本解及局部可解性

In this paper it is proved that local fundamental solution exists in some space W^m(H_n) (m∈Z), if the left invariant differential operator on the Heisenberg group H_n satisfies certain condition. The main results are:l.Let L be a left invariant differential operator on H_n. If there exist R≥0, r,s∈R and operators {B_λ|λ∈Γ_R} ∈V^s(Γ_R, M^r) such that, for almost all λ∈Γ_R, B_λ is the right inverse of Ⅱ_λ(L), then there exists E∈W^m(H_n) (when m≥0 or m even) or E∈W^m-1(H_n) (when m<0 and odd) such that LE =δ(near the origie) Where m=min([r],-[2s]-n-2); 2. Let L(W,T) be of the form (3.1). If there exist R≥0 and r,s∈R such that when |λ|≥R,(?) and C_λ≥ C|λ|^x(C>0), then the same conclusion as above holds with m=min(-[2r]-n-2,[-2s]-n-2).     

The condensate 〈(A µ 2 )〉 in commutative and noncommutative theories

We show that the gauge invariance of the operator ∫ dx tr(A _μ ² −2/(gξ)x ^υθ_μυ A ^μ) in a noncommutative gauge theory does not lead to the gauge independence of its vacuum condensate. We obtain the generalized Ward identities for Green’s functions containing the operator lim_Ω→∞(1/Ω)∫_Ω dx tr (A _μ ² ) in commutative and noncommutative gauge theories. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 148, No. 3, pp. 350–356, September, 2006.     

Boundedness of commutators on Hardy type spaces

Let [b, T] be the commutator of the function b ∈ Lipβ(Rn) (0 ＜β≤ 1) and the CalderónZygmund singular integral operator T. The authors study the boundedness properties of [b, T] on the classical Hardy spaces and the Herz-type Hardy spaces in non-extreme cases. For the boundedness of these commutators in extreme cases, some characterizations are also given. Moreover, the authors prove that these commutators are bounded from Hardy type spaces to the weak Lebesgue or Herz spaces in extreme cases.     

BOUNDEDNESS OF SEVERAL OPERATORS ON MARTINGALE SPACES AND THE GEOMETRY OF BANACH SPACES

The aim of this paper is establishing some inequalities of several operators on Banach-space-valued martingales and using them to give some characterizations of geometrical properties of Banach spaces. In particular, the Φ-function nequalitities of sharp operators f_p~#, f_p~#, p-variation operators W_p, W_p and the martingale tranform operator T_v are discussed. It is proved that the boundedness of these operators characterizes the smoothness, convexity and UMD-property of Banach spaces.     

一类振荡奇异积分算子在Triebel-Lizorkin空间的有界性

The boundedness on Triebel-Lizorkin spaces of oscillatory singular integral operator T in the form ei|x|aΩ(x)|x|-n is studied,where a∈R,a≠0,1 and Ω∈L1(Sn-1) is homogeneous of degree zero and satisfies certain cancellation condition.When kernel Ω(x′)∈Llog L(Sn-1),the α,qp(Rn) boundedness of the above operator is obtained.Meanwhile,when Ω(x) satisfies L1-Dini condition,the above operator Tis bounded on 0,11(Rn).     

Hilbert-Schmidt类上的k-拟亚正规算子

An operator T acting on a Hilbert space H is called k- quasihyponormal if {T} =T^*k (T^*T-TT^*)T^k≥0 . Let A and B be two operators on H, one can obtain an operator τ =τ_AB on the class l₂ of all Hilbert-Schmidt operators on H in such a way that τ(X)=AXB for every X∈l₂. In this note the authors show that     

Characterizations of Function Spaces via Boundedness of Commutators

In this paper, we give some creative characterizations of Campanato spaces via the boundedness of commutators associated with the Calder ′on-Zygmund singular integral operator, fractional integrals and Hardy type operators. Furthermore, we put forward a few problems on the characterizations of Campanato type spaces via the boundedness of commutators.     

α-Bloch空间到H∞的加权复合算子

The article not only presents the boundedness and compactness of the weighted composition operator fromα-Bloch spaces(or littleα-Bloch spaces) to H~∞,but also gives some estimates for the norm of the weighted composition operator.     

关于算子─（▽—ia）2＋Ⅴ的性质（Ⅰ）

In this paper,we consider Schrodinger forms (operators) with singular magnetic vectorpotentials ─(▽—ia）²+Ⅴ. We prove that when the negative part V_{_} of electric potentialV satisfies(?) in dependentof V and a=(a₁,a₂,…,a_N)∈L_loc²(R^N)^N, ─(▽—ia）²+Ⅴ has essential self-adjointextension F and it is the only self-adjoint realization of ─(▽—ia）²+Ⅴ. Moreover,We consider the continuity of (a,V) respect to a and V in the sense of strong resolvent.     

Function characterizations via commutators of Hardy operator

This paper is a summary of the research on the characterizations of central function spaces by the author and his collaborators in the past ten years.More precisely,the author gives some characterizations of central Campanato spaces via the boundedness and compactness of commutators of Hardy operator.     

Hqp(01)空间中的多项式最佳逼近问题

In this paper, we obtained two direct theorems and a inverse theorem on the best approximation by polynomials in H_q^p(01) spaces. The results obtained in this paper are just some direct extensions from the case p= 1 to the case 0相似文献   

GCD和GCUD矩阵行列式的一个不等式（英）

Let S = {x₁, x₂,..., x_n} be a set of distinct positive integers. The n x n matrix (S) whose i, j-entry is the greatest common divisor (x_i, x_j) of x_i and x_j is called the GCD matrix on S. A divisor d of x is said to be a unitary divisor of x if (d, x/d) = 1. The greatest common unitary divisor (GCUD) matrix (S^**) is defined analogously. We show that if S is both GCD-closed and GCUD-closed, then det(S^**) ≥ det(S), where the equality holds if and Only if (S^**) = (S).