Levi foliations in pseudoconvex boundaries and vector fields that commute approximately with d-bar

The intrinsic geometry on bounded pseudoconvex domains

The Diederich--Fornæss index has been introduced since 1977 to classify bounded pseudoconvex domains. In this article, we derive several intrinsic, geometric conditions on boundary of domains for arbitrary indexes. Many results, in the past, by various mathematicians estimated the index by assuming some properties of domains. Our motivation of this paper is, the other way around, to look for how the index effects properties and shapes of domains. Especially, we look for a necessary condition of all bounded pseudoconvex domains $Ω\subset\mathbb{C}^2$ with the Diederich--Fornæss index 1. We also…

Remarks on homogeneous manifolds satisfying Levi conditions

Homogeneous complex manifolds satisfying various types of Levi conditions are considered. Classical results which were of particular interest to Andreotti are recalled. Convexity and concavity properties of flag domains are discussed in some detail. A precise classification of pseudoconvex flag domains is given. It is shown that flag domains which are in a certain sense generic are pseudoconcave.

Geometric Analysis on the Diederich-Fornæss Index

We derive a sufficient condition on a bounded pseudoconvex domain $Ω\subset\mathbb{C}^2$ with smooth boundary such that $-(-ρ)^η$ is plurisubharmonic on $Ω$ for $η>0$ arbitrarily close to $1$ (the supremum of $η$ is called Diederich-Fornæss index, see Definition (df)). This condition (see Theorem prop) extends a theorem of Fornæss and Herbig in 2007 and only requires restriction on Levi-flat sets of the boundary $\partialΩ$. Since the condition is on Levi-flat sets, it contains more geometric information. As an application of this new condition, we discuss how the geometry of the Levi-flat set…

Strongly pseudoconvex domains as subvarieties of complex manifolds

In this paper (a sequel to B. Drinovec Drnovsek and F. Forstneric, Holomorphic curves in complex spaces, Duke Math. J. 139 (2007), 203-253) we obtain existence and approximation results for closed complex subvarieties that are normalized by strongly pseudoconvex Stein domains. Our sufficient condition for the existence of such subvarieties in a complex manifold is expressed in terms of the Morse indices and the number of positive Levi eigenvalues of an exhaustion function on the manifold. Examples show that our condition cannot be weakened in general. Optimal results are obtained for subvariet…

Sufficient condition for compactness of the $\overline{\partial}$-Neumann operator using the Levi core

On a smooth, bounded pseudoconvex domain $Ω$ in $\mathbb{C}^n$, to verify that Catlin's Property ($P$) holds for $bΩ$, it suffices to check that it holds on the set of D'Angelo infinite type boundary points. In this note, we consider the support of the Levi core, $S_{\mathfrak{C}(\mathcal{N})}$, a subset of the infinite type points, and show that Property ($P$) holds for $bΩ$ if and only if it holds for $S_{\mathfrak{C}(\mathcal{N})}$. Consequently, if Property ($P$) holds on $S_{\mathfrak{C}(\mathcal{N})}$, then the $\overline{\partial}$-Neumann operator $N_1$ is compact on $Ω$.

Kähler-Einstein fillings

We show that on an open bounded smooth strongly pseudoconvex subset of $\CC^{n}$, there exists a Kähler-Einstein metric with positive Einstein constant, such that the metric restricted to the Levi distribution of the boundary is conformal to the Levi form. To achieve this, we solve an associated complex Monge-Ampère equation with Dirichlet boundary condition. We also prove uniqueness under some more assumptions on the open set.

Estimates for the $\bar\partial$-Neumann problem and nonexistence of Levi-flat hypersurfaces in $CP^n$

Let $Ω$ be a pseudoconvex domain with $C^2$-smooth boundary in $\mathbb CP^n$. We prove that the $\bar\partial-Neumann operator $N$ exists for $(p,q)$-forms on $Ω$. Furthermore, there exists a $t_0>0$ such that the operators $N$, $\bar\partial^*N$, $\bar\partial N$ and the Bergman projection are regular in the Sobolev space $W^t (\barΩ) $ for $t<t_0$. The boundary estimates above have applications in complex geometry. We use the estimates to prove the nonexistence of $C^{2, α}$ real Levi-flat hypersurfaces in $\mathbb CP^n$. We also show that there exist no non-zero $L^2$-holomorphic $(p, 0)$-…

Diederich-Fornæss指数与复Green算子的全局正则性：具有可比Levi特征值的领域

Diederich-Fornæss index and global regularity of the complex Green operator: domains with comparable Levi eigenvalues

本文研究了具有可比Levi特征值的伪凸领域中复Green算子的全局正则性，证明在Diederich-Fornaess指数为一的情况下，特定范围内的q值使得算子具有全局正则性。

Complex Manifolds In $Q$-Convex Boundaries

We consider a smooth boundary bΩwhich is q-convex in the sense that its Levi-form has positive trace on every complex q-plane. We prove that bΩis tangent of infinite order to the complexification of each of its submanifolds which is complex tangential and of finite bracket type. This generalizes Diederich-Fornaess [Annals 1978] from pseudoconvex to q-convex domains. We also readily prove that the rows of the Levi-form are (1/2)-subelliptic multipliers for the di-bar-Neumann problem on q-forms (cf. Ho [Math. Ann. 1991]). This allows to run the Kohn algorithm of [Acta Math. 1979] in the chain of…

On geometry of $2$-nondegenerate CR structures of hypersurface type and flag structures on leaf spaces of Levi foliations

We construct canonical absolute parallelisms over real-analytic manifolds equipped with $2$-nondegenerate, hypersurface-type CR structures of arbitrary odd dimension not less than $7$ whose Levi kernel has constant rank belonging to a broad subclass of CR structures that we label as recoverable. For this we develop a new approach based on a reduction to a special flag structure, called the dynamical Legendrian contact structure, on the leaf space of the CR structure's associated Levi foliation. This extends the results of Porter-Zelenko [20] from the case of regular CR symbols constituting a d…

严格伪凸域上Toeplitz算子的半经典谱渐近

Semi-classical spectral asymptotics of Toeplitz operators on strictly pseudodonvex domains

本文研究严格伪凸域上Toeplitz算子的半经典谱渐近，证明其谱投影核为复相位Fourier积分算子，并给出边界上首项为$k^{n+1}$的渐近展开。

Boundary invariants and the closed range property for $\bar\partial$

This paper provides a connection between two distinct branches of research in CR geometry -- namely, analytic and geometric conditions that suffice to establish the closed range of the Cauchy-Riemann operator and CR invariants on CR manifolds. Specifically, we work on not necessarily pseudoconvex domains $Ω\subset\mathbb{C}^n$ and define third and fourth order CR invariants on $\bd\Om$ and show that these invariants provide enough information to establish closed range for the $\bar\partial$-Laplacian in $L^2_{(0,q)}(Ω)$ for a given, fixed $q$. The closed range estimates follow from our previou…