扭化的Atiyah-Singer算子(I)

本文证明黎曼流表上的ｄｅ Ｒｈａｍ以及Ｓｉｇｎａｔｕｒｅ算子都同构于扭化的Ａｔｉｙａｈ－Ｓｉｎｇｅｒ算子。这两类算子的局部指数定理和局部Ｌｅｆｓｃｈｅｔｚ不动点公式都可以从扭化的Ａｔｉｙａｈ－Ｓｉｎｇｅｒ算子得到。     

de Rham－Hodge－Signature算子的局部指标定理

整体的Ａｔｉｙａｈ－Ｓｉｎｇｅｒ指标定理对于一般的椭圆微分算子都成立．但对于局部指标定理来说，人们只能对具体的算子给予证明．并且各种情况需个别处理．由［６］知本文中证得的ｄｅＲｈａｍ－Ｈｏｄｇｅ－Ｓｉｇｎａｔｕｒｅ算子的局部指标既不是α型也不是β型的．这和经典的椭圆算子情形不同．     

de Rham－Hodge－Signature算子的局部指标定理

整体的Ａｔｉｙａｈ－Ｓｉｎｇｅｒ指标定理对于一般的椭圆微分算子都成立．但对于局部指标定理来说，人们只能对具体的算子给予证明．并且各种情况需个别处理．由［６］知本文中证得的ｄｅＲｈａｍ－Ｈｏｄｇｅ－Ｓｉｇｎａｔｕｒｅ算子的局部指标既不是α型也不是β型的．这和经典的椭圆算子情形不同．     

本质正规算子的迹类算子扰动

本文利用ＢＤＦ定理以及构造技巧证明了关于本质正规算子的Ｐｅａｒｃｙ－Ｓａｌｉｎａｓ定理．作为此定理的应用，证明了本质正规算子可以通过迹类算子的小扰动成为不可约算子．     

D×D上的Toeplitz型与Hankel型算子

本文给出了空间Ｌ￣ａ，２（Ｄ×Ｄ，）的一个完全正交分解，定义了一系列Ｔｏｅｐｌｉｔｚ型与Ｈａｎｋｅｌ型算子，并且证明了它们的有界性，紧性及其Ｓｃｈａｔｔｅｎ－ｖｏｎＮｅｕｍａｎｎ性质．     

多元Bernstein-Durrmeyer算子L~p逼近的Steckin-Marchaud型不等式

本文给出多元 Ｂｅｒｎｓｔｅｉｎ－Ｄｕｒｒｍｅyｅｒ算子 ＬＰ逼近的 Ｓｔｅｃｋｉｎ－Ｍａｒｃｈａｕｄ型不等式,从该不等式得到多元Ｂernstein-Ｄurrmeyer算子Ｌp对逼近的特征刻划定理．     

Non-singularSaffman-taylorFinger1

Ｎｏｎ－ｓｉｎｇｕｌａｒＳａｆｆｍａｎ－ｔａｙｌｏｒＦｉｎｇｅｒ１ＫａｉＨｕａＺＨＡＯＨｕｉｄａｎＹＵ（Ｄｅｐａｒｔｍｅｎｔｏｆｐｈｙｓｉｃｓ，ＣｅｎｔｅｒｆｏｒＮｏｎｌｉｎｅａｒＳｃｉｅｎｃｅ，ＰｅｋｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１００...     

Toeplitz算子空间的W—闭包

本文讨论了Ｔｏｅｐｌｉｔｚ算子空间的Ｗ－闭包，我们证明了Ｂｅｒｇｍａｎ空间Ｌ＾２ａ（Ｄ）上全体Ｔｏｅｐｌｉｔｚ算子的Ｗ闭包等于Ｂ（Ｌ＾２ａ（Ｄ）（定理１），另外，我们给出Ｃ＾ｍ（ｎ＞１）中单位球面Ｓ上的Ｈａｒｄｙ空间Ｈ＾２（Ｓ）上的Ｔｏｅｐｌｉｔｚ算子的一个有趣刻划（命题２）。     

一类退化椭圆算子的逆

本文利用在最近发展起来的拟微分算子非齐次象征运算理论，研究了一类形如Ｄｘ１２＋ｘ１２ｋＤｘ２２的退化椭圆算子的基本解．根据Ｒｏｔｈｓｃｈｉｌｄ－Ｓｔｅｉｎ［６］的工作。这些基本解都是奇异积分算子，本文的主要结果就是证明了它们事实上是拟微分算子，其象征属于广义的Ｈｏｒｍａｎｄｅｒ象征类．因此证明了在相应的带权Ｓｏｂｏｌｅｖ空间上，这类退化椭圆算子具有类似于椭圆算子的基本性质．     

Bergman空间A~2上的Toeplitz与Hankel算子的紧性

本文给出Ｂｅｒｇｍａｎ空间Ａ２上的Ｔｏｅｐｌｉｔｚ算子Ｔｆ与Ｈａｎｋｅｌ算子Ｈｆ（ｆ∈Ｌ∞）是紧的充要条件，从而解决Ｓ．Ａｘｌｅｒ分别于１９８４和１９８５年提出的一个问题．     

On the spectrum of the twisted Dolbeault Laplacian over Kähler manifolds

We use Dirac operator techniques to a establish sharp lower bound for the first eigenvalue of the Dolbeault Laplacian twisted by Hermitian-Einstein connections on vector bundles of negative degree over compact Kähler manifolds.     

Twisted holomorphic forms on generalized flag varieties

In this paper we prove some vanishing theorems for the twisted Dolbeault cohomology of the complete flag varieties associated to a simple, simply connected algebraic group.     

Perturbed Dolbeault operators and the homology Todd class

This paper discusses the role played by perturbed Dolbeault operators in relating the coherent sheaf and elliptic operator perspectives on the homology of projective varieties. Among the consequences are index formulas for perturbed Dolbeault operators.

     

Dolbeault cohomology of G /( P,P )

Let G be a complex connected semi-simple Lie group, with parabolic subgroup P. Let (P,P) be its commutator subgroup. The generalized Borel-Weil theorem on flag manifolds has an analogous result on the Dolbeault cohomology . Consequently, the dimension of is either 0 or . In this paper, we show that the Dolbeault operator has closed image, and apply the Peter-Weyl theorem to show how q determines the value 0 or . For the case when P is maximal, we apply our result to compute the Dolbeault cohomology of certain examples, such as the punctured determinant bundle over the Grassmannian. Received: September 2, 1997; in final form February 9, 1998     

Extrinsic Bounds for Eigenvalues of the Dirac Operator

We derive upper eigenvalue bounds for the Dirac operator of a closed hypersurface in a manifold with Killing spinors such as Euclidean space, spheres or hyperbolic space. The bounds involve the Willmore functional. Relations with the Willmore inequality are briefly discussed. In higher codimension we obtain bounds on the eigenvalues of the Dirac operator of the submanifold twisted with the spinor bundle of the normal bundle.     

Multiplets of representations, twisted Dirac operators and Vogan's conjecture in affine setting

We extend classical results of Kostant et al. on multiplets of representations of finite-dimensional Lie algebras and on the cubic Dirac operator to the setting of affine Lie algebras and twisted affine cubic Dirac operator. We prove in this setting an analogue of Vogan's conjecture on infinitesimal characters of Harish-Chandra modules in terms of Dirac cohomology. For our calculations we use the machinery of Lie conformal and vertex algebras.     

扭的Heisenberg-Virasoro顶点算子代数的一个特征化（英文）

The twisted Heisenberg-Virasoro algebra is the universal central extension of the Lie algebra of differential operators on a circle of order at most one. In this paper, we first study the variety of semi-conformal vectors of the twisted Heisenberg-Virasoro vertex operator algebra, which is a finite set consisting of two nontrivial elements. Based on this property,we also show that the twisted Heisenberg-Virasoro vertex operator algebra is a tensor product of two vertex operator algebras. Moreover, associating to properties of semi-conformal vectors of the twisted Heisenberg-Virasoro vertex operator algebra, we charaterized twisted Heisenberg-Virasoro vertex operator algebras. This will be used to understand the classification problems of vertex operator algebras whose varieties of semi-conformal vectors are finite sets.     

Local conformal nets arising from framed vertex operator algebras

We apply an idea of framed vertex operator algebras to a construction of local conformal nets of (injective type III₁) factors on the circle corresponding to various lattice vertex operator algebras and their twisted orbifolds. In particular, we give a local conformal net corresponding to the moonshine vertex operator algebras of Frenkel-Lepowsky-Meurman. Its central charge is 24, it has a trivial representation theory in the sense that the vacuum sector is the only irreducible DHR sector, its vacuum character is the modular invariant J-function and its automorphism group (the gauge group) is the Monster group. We use our previous tools such as α-induction and complete rationality to study extensions of local conformal nets.     

Equivariant Holomorphic Morse Inequalities III: Non-isolated Fixed Points

We prove the equivariant holomorphic Morse inequalities for a holomorphic torus action on a holomorphic vector bundle over a compact K?hler manifold when the fixed-point set is not necessarily discrete. Such inequalities bound the twisted Dolbeault cohomologies of the K?hler manifold in terms of those of the fixed-point set. We apply the inequalities to obtain relations of Hodge numbers of the connected components of the fixed-point set and the whole manifold. We also investigate the consequences in geometric quantization, especially in the context of symplectic cutting. Received: February 1997, Revised version: August 1997