Let X_1 and X_2 be two compact connected strongly pseudoconvex embeddable Cauchy-Riemann(CR) manifolds of dimensions 2m-1 and 2n-1 in C^(m+1)and C^(n+1), respectively. We introduce the ThomSebastiani sum X = X_1 ⊕X_2...Let X_1 and X_2 be two compact connected strongly pseudoconvex embeddable Cauchy-Riemann(CR) manifolds of dimensions 2m-1 and 2n-1 in C^(m+1)and C^(n+1), respectively. We introduce the ThomSebastiani sum X = X_1 ⊕X_2which is a new compact connected strongly pseudoconvex embeddable CR manifold of dimension 2m+2n+1 in C^(m+n+2). Thus the set of all codimension 3 strongly pseudoconvex compact connected CR manifolds in Cn+1for all n 2 forms a semigroup. X is said to be an irreducible element in this semigroup if X cannot be written in the form X_1 ⊕ X_2. It is a natural question to determine when X is an irreducible CR manifold. We use Kohn-Rossi cohomology groups to give a necessary condition of the above question. Explicitly,we show that if X = X_1 ⊕ X_2, then the Kohn-Rossi cohomology of the X is the product of those Kohn-Rossi cohomology coming from X_1 and X_2 provided that X_2 admits a transversal holomorphic S^1-action.展开更多
Strongly pseudoconvex CR manifolds are boundaries of Stein varieties with isolated normal singularities.We introduce a series of new invariant plurigeneraδm,m∈Z+for a strongly pseudoconvex CR manifold.The main purpo...Strongly pseudoconvex CR manifolds are boundaries of Stein varieties with isolated normal singularities.We introduce a series of new invariant plurigeneraδm,m∈Z+for a strongly pseudoconvex CR manifold.The main purpose of this paper is to present the following result:Let X1and X2be two compact strongly pseudoconvex embeddable CR manifolds of dimension 2n-1 3.If there is a non-constant CR morphism from X1to X2,thenδm(X2)δm(X1)whereδm(Xi)is the plurigeneus of Xi(see Definition 2.4).展开更多
The necessary and sufficient conditions for an arbitrary almost Hermitian manifold to be an R 2 or a cR 2 manifold are established. Some examples of non Khlerian and non nearly Khlerian R 2 and cR 2 manifolds are ...The necessary and sufficient conditions for an arbitrary almost Hermitian manifold to be an R 2 or a cR 2 manifold are established. Some examples of non Khlerian and non nearly Khlerian R 2 and cR 2 manifolds are given.展开更多
This paper deals with the study of CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non-metric connection. Nijenhuis tensor, integrability conditions for some distributions on CR-submanifolds ...This paper deals with the study of CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non-metric connection. Nijenhuis tensor, integrability conditions for some distributions on CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non- metric connection are discussed.展开更多
In this paper,it is proved that the Sasakian anti-holomorphic submanifolds of a Kaehlerian man-ifold is characterized by D-totally umbilical,and some curvature properties of the CR-submanifolds are ob-tained.
In this paper, we study geodesic contact CR-lightlike submanifolds and geodesic screen CR-lightlike (SCR) submanifolds of indefinite Sasakian manifolds. Some necessary and sufficient conditions for totally geodesic, m...In this paper, we study geodesic contact CR-lightlike submanifolds and geodesic screen CR-lightlike (SCR) submanifolds of indefinite Sasakian manifolds. Some necessary and sufficient conditions for totally geodesic, mixed geodesic, -geodesic and -geodesic contact CR-lightlike submanifolds and SCR submanifolds are obtained.展开更多
We perform detailed computations of Lie algebras of infinitesimal CR-automorphisms associated to three specific model real analytic CR-generic submanifolds in C9by employing differential algebra computer tools—mostly...We perform detailed computations of Lie algebras of infinitesimal CR-automorphisms associated to three specific model real analytic CR-generic submanifolds in C9by employing differential algebra computer tools—mostly within the Maple package DifferentialAlgebra—in order to automate the handling of the arising highly complex linear systems of PDE’s.Before treating these new examples which prolong previous works of Beloshapka,of Shananina and of Mamai,we provide general formulas for the explicitation of the concerned PDE systems that are valid in arbitrary codimension k 1 and in any CR dimension n 1.Also,we show how Ritt’s reduction algorithm can be adapted to the case under interest,where the concerned PDE systems admit so-called complex conjugations.展开更多
In this paper, we discuss some recent studies on the complex structure of an isolated normal singularity by using the information from its link. We also give some open problems to be further pursued.
基金supported by National Natural Science Foundation of China(Grant Nos.11531007 and 11401335)Start-Up Fund from Tsinghua University and Tsinghua University Initiative Scientific Research Program
文摘Let X_1 and X_2 be two compact connected strongly pseudoconvex embeddable Cauchy-Riemann(CR) manifolds of dimensions 2m-1 and 2n-1 in C^(m+1)and C^(n+1), respectively. We introduce the ThomSebastiani sum X = X_1 ⊕X_2which is a new compact connected strongly pseudoconvex embeddable CR manifold of dimension 2m+2n+1 in C^(m+n+2). Thus the set of all codimension 3 strongly pseudoconvex compact connected CR manifolds in Cn+1for all n 2 forms a semigroup. X is said to be an irreducible element in this semigroup if X cannot be written in the form X_1 ⊕ X_2. It is a natural question to determine when X is an irreducible CR manifold. We use Kohn-Rossi cohomology groups to give a necessary condition of the above question. Explicitly,we show that if X = X_1 ⊕ X_2, then the Kohn-Rossi cohomology of the X is the product of those Kohn-Rossi cohomology coming from X_1 and X_2 provided that X_2 admits a transversal holomorphic S^1-action.
基金supported by the Start-Up Fund from Tsinghua University and National Natural Science Foundation of China(Grant No.11401335)
文摘Strongly pseudoconvex CR manifolds are boundaries of Stein varieties with isolated normal singularities.We introduce a series of new invariant plurigeneraδm,m∈Z+for a strongly pseudoconvex CR manifold.The main purpose of this paper is to present the following result:Let X1and X2be two compact strongly pseudoconvex embeddable CR manifolds of dimension 2n-1 3.If there is a non-constant CR morphism from X1to X2,thenδm(X2)δm(X1)whereδm(Xi)is the plurigeneus of Xi(see Definition 2.4).
文摘The necessary and sufficient conditions for an arbitrary almost Hermitian manifold to be an R 2 or a cR 2 manifold are established. Some examples of non Khlerian and non nearly Khlerian R 2 and cR 2 manifolds are given.
文摘This paper deals with the study of CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non-metric connection. Nijenhuis tensor, integrability conditions for some distributions on CR-submanifolds of a nearly trans-Sasakian manifold with a semi symmetric non- metric connection are discussed.
文摘In this paper,it is proved that the Sasakian anti-holomorphic submanifolds of a Kaehlerian man-ifold is characterized by D-totally umbilical,and some curvature properties of the CR-submanifolds are ob-tained.
文摘In this paper, we study geodesic contact CR-lightlike submanifolds and geodesic screen CR-lightlike (SCR) submanifolds of indefinite Sasakian manifolds. Some necessary and sufficient conditions for totally geodesic, mixed geodesic, -geodesic and -geodesic contact CR-lightlike submanifolds and SCR submanifolds are obtained.
基金supported by the Center for International Scientific Studies and Collaboration(CISSC)and French Embassy in TehranThe resend of the first and second authors was in part supported by grants from IPM(Grant Nos.91530040 and 92550420)
文摘We perform detailed computations of Lie algebras of infinitesimal CR-automorphisms associated to three specific model real analytic CR-generic submanifolds in C9by employing differential algebra computer tools—mostly within the Maple package DifferentialAlgebra—in order to automate the handling of the arising highly complex linear systems of PDE’s.Before treating these new examples which prolong previous works of Beloshapka,of Shananina and of Mamai,we provide general formulas for the explicitation of the concerned PDE systems that are valid in arbitrary codimension k 1 and in any CR dimension n 1.Also,we show how Ritt’s reduction algorithm can be adapted to the case under interest,where the concerned PDE systems admit so-called complex conjugations.
文摘In this paper, we discuss some recent studies on the complex structure of an isolated normal singularity by using the information from its link. We also give some open problems to be further pursued.
