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1.
Our main theorem is a characterization of a totally geodesic K?hler immersion of a complex n-dimensional K?hler manifold M
n
into an arbitrary complex (n + p)-dimensional K?hler manifold
by observing the extrinsic shape of K?hler Frenet curves on the submanifold M
n
. Those curves are closely related to the complex structure of M
n
. 相似文献
2.
A locally conformally Kähler (LCK) manifold M is one which is covered by a Kähler manifold ${\widetilde M}A locally conformally K?hler (LCK) manifold M is one which is covered by a K?hler manifold [(M)\tilde]{\widetilde M} with the deck transformation group acting conformally on [(M)\tilde]{\widetilde M}. If M admits a holomorphic flow, acting on [(M)\tilde]{\widetilde M} conformally, it is called a Vaisman manifold. Neither the class of LCK manifolds nor that of Vaisman manifolds is stable
under small deformations. We define a new class of LCK-manifolds, called LCK manifolds with potential, which is closed under
small deformations. All Vaisman manifolds are LCK with potential. We show that an LCK-manifold with potential admits a covering
which can be compactified to a Stein variety by adding one point. This is used to show that any LCK manifold M with potential, dim M ≥ 3, can be embedded into a Hopf manifold, thus improving similar results for Vaisman manifolds Ornea and Verbitsky (Math
Ann 332:121–143, 2005). 相似文献
3.
A class of minimal almost complex submanifolds of a Riemannian manifold
with a parallel quaternionic structure Q, in particular of a 4-dimensional oriented Riemannian manifold, is studied. A notion of Kähler submanifold is defined. Any Kähler submanifold is pluriminimal. In the case of a quaternionic Kähler manifold
of non zero scalar curvature, in particular, when
is an Einstein, non Ricci-flat, anti-self-dual 4-manifold, we give a twistor construction of Kähler submanifolds M2n of maximal possible dimension 2n. More precisely, we prove that any such Kähler submanifold M2n of
is the projection of a holomorphic Legendrian submanifold
of the twistor space
of
, considered as a complex contact manifold with the natural holomorphic contact structure
. Any Legendrian submanifold of the twistor space
is defined by a generating holomorphic function. This is a natural generalization of Bryants construction of superminimal surfaces in S4=P1. Mathematics Subject Classification (1991) Primary: 53C40; Secondary: 53C55 相似文献
4.
We survey recent developments which led to the proof of the Benson-Gordon conjecture on Kähler quotients of solvable Lie groups. In addition, we prove that the Albanese morphism of a Kähler manifold which is a homotopy torus is a biholomorphic map. The latter result then implies the classification of compact aspherical Kähler manifolds with (virtually) solvable fundamental group up to biholomorphic equivalence. They are all biholomorphic to complex manifolds which are obtained as a quotient of $\mathbb{C}^{n}We survey recent developments which led to the proof of the Benson-Gordon conjecture on K?hler quotients of solvable Lie groups.
In addition, we prove that the Albanese morphism of a K?hler manifold which is a homotopy torus is a biholomorphic map. The
latter result then implies the classification of compact aspherical K?hler manifolds with (virtually) solvable fundamental
group up to biholomorphic equivalence. They are all biholomorphic to complex manifolds which are obtained as a quotient of
\mathbbCn\mathbb{C}^{n} by a discrete group of complex isometries. 相似文献
5.
Arvid Perego 《Mathematische Annalen》2010,346(2):367-391
The aim of this work is to show that the moduli space M
10 introduced by O’Grady is a 2-factorial variety. Namely, M
10 is the moduli space of semistable sheaves with Mukai vector v: = (2, 0, −2) in
Hev(X,\mathbbZ){H^{ev}(X,\mathbb{Z})} on a projective K3 surface X. As a corollary to our construction, we show that the Donaldson morphism gives a Hodge isometry between v^{v^{\perp}} (sublattice of the Mukai lattice of X) and its image in
H2 ([(M)\tilde]10, \mathbbZ){H^{2} (\widetilde{M}_{10}, \mathbb{Z})}, lattice with respect to the Beauville form of the 10-dimensional irreducible symplectic manifold [(M)\tilde]10{\widetilde{M}_{10}}, obtained as symplectic resolution of M
10. Similar results are shown for the moduli space M
6 introduced by O’Grady to produce its 6-dimensional example of irreducible symplectic variety. 相似文献
6.
V. V. Konnov 《Journal of Mathematical Sciences》2007,141(1):1004-1015
A nondegenerate m-pair (A, Ξ) in an n-dimensional projective space ?P n consists of an m-plane A and an (n ? m ? 1)-plane Ξ in ?P n , which do not intersect. The set \(\mathfrak{N}_m^n \) of all nondegenerate m-pairs ?P n is a 2(n ? m)(n ? m ? 1)-dimensional, real-complex manifold. The manifold \(\mathfrak{N}_m^n \) is the homogeneous space \(\mathfrak{N}_m^n = {{GL(n + 1,\mathbb{R})} \mathord{\left/ {\vphantom {{GL(n + 1,\mathbb{R})} {GL(m + 1,\mathbb{R})}}} \right. \kern-\nulldelimiterspace} {GL(m + 1,\mathbb{R})}} \times GL(n - m,\mathbb{R})\) equipped with an internal Kähler structure of hyperbolic type. Therefore, the manifold \(\mathfrak{N}_m^n \) is a hyperbolic analogue of the complex Grassmanian ?G m,n = U(n+1)/U(m+1) × U(n?m). In particular, the manifold of 0-pairs \(\mathfrak{N}_m^n {{GL(n + 1,\mathbb{R})} \mathord{\left/ {\vphantom {{GL(n + 1,\mathbb{R})} {GL(1,\mathbb{R})}}} \right. \kern-\nulldelimiterspace} {GL(1,\mathbb{R})}} \times GL(n,\mathbb{R})\) is a hyperbolic analogue of the complex projective space ?P n = U(n+1)/U(1) × U(n). Similarly to ?P n , the manifold \(\mathfrak{N}_m^n \) is a Kähler manifold of constant nonzero holomorphic sectional curvature (relative to a hyperbolic metrics). In this sense, \(\mathfrak{N}_0^n \) is a hyperbolic spatial form. It was proved in [6] that the manifold of 0-pairs \(\mathfrak{N}_0^n \) is globally symplectomorphic to the total space T*?P n of the cotangent bundle over the projective space ?P n . A generalization of this result (see [7]) is as follows: the manifold of nondegenerate m-pairs \(\mathfrak{N}_m^n \) is globally symplectomorphic to the total space T*?G m,n of the cotangent bundle over the Grassman manifold ?G m,n of m-dimensional subspaces of the space ?P n .In this paper, we study the canonical Kähler structure on \(\mathfrak{N}_m^n \). We describe two types of submanifolds in \(\mathfrak{N}_m^n \), which are natural hyperbolic spatial forms holomorphically isometric to manifolds of 0-pairs in ?P m +1 and in ?P n?m , respectively. We prove that for any point of the manifold \(\mathfrak{N}_m^n \), there exist a 2(n ? m)-parameter family of 2(m + 1)-dimensional hyperbolic spatial forms of first type and a 2(m + 1)-parameter family of 2(n ? m)-dimensional hyperbolic spatial forms of second type passing through this point. We also prove that natural hyperbolic spatial forms of first type on \(\mathfrak{N}_m^n \) are in bijective correspondence with points of the manifold \(\mathfrak{N}_{m + 1}^n \) and natural hyperbolic spatial forms of second type on \(\mathfrak{N}_m^n \) are in bijective correspondence with points of the manifolds \(\mathfrak{N}_{m + 1}^n \). 相似文献
7.
8.
Yuguang ZHANG 《数学年刊B辑(英文版)》2007,28(4):421-428
Compact Kähler manifolds with semi-positive Ricci curvature have been investigated by various authors. From Peternell’s work, if M is a compact Kähler n-manifold with semi-positive Ricci curvature and finite fundamental group, then the universal cover has a decomposition \( \ifmmode\expandafter\tilde\else\expandafter\~\fi{M} \cong X_{1} \times \cdots \times X_{m} \), where X j is a Calabi-Yau manifold, or a hyperKähler manifold, or X j satisfies H 0(X j , Ω p ) = 0. The purpose of this paper is to generalize this theorem to almost non-negative Ricci curvature Kähler manifolds by using the Gromov-Hausdorff convergence. Let M be a compact complex n-manifold with non-vanishing Euler number. If for any ∈ > 0, there exists a Kähler structure (J ∈, g ∈) on M such that the volume \({\text{Vol}}_{{g_{ \in } }} {\left( M \right)} < V\), the sectional curvature |K(g ∈)| < Λ2, and the Ricci-tensor Ric(g ∈)> ?∈g ∈, where V and Λ are two constants independent of ∈. Then the fundamental group of M is finite, and M is diffeomorphic to a complex manifold X such that the universal covering of X has a decomposition, \( \ifmmode\expandafter\tilde\else\expandafter\~\fi{X} \cong X_{1} \times \cdots \times X_{s} \), where X i is a Calabi-Yau manifold, or a hyperKähler manifold, or X i satisfies H 0(X i , Ω p ) = {0}, p > 0. 相似文献
9.
Misha Verbitsky 《Selecta Mathematica, New Series》2005,10(4):551-559
For any subvariety of a compact holomorphic symplectic K?hler manifold, we define the symplectic Wirtinger number W(X). We show that
W(X) \leqslant 1,W(X) \leqslant 1, and the equality is reached if and only if the subvariety
X ì MX \subset M is trianalytic, i.e. compatible with the hyperk?hler structure on M. For a sequence
X1 ? X2 ? ?Xn ? MX_1 \to X_2 \to \ldots X_n \to M of immersions of simple holomorphic symplectic manifolds, we show that
W( X1 ) \leqslant W( X2 ) \leqslant ?\leqslant W( Xn ).W\left( {X_1 } \right) \leqslant W\left( {X_2 } \right) \leqslant \ldots \leqslant W\left( {X_n } \right). 相似文献
10.
Manuel del Pino Michal Kowalczyk Juncheng Wei Jun Yang 《Geometric And Functional Analysis》2010,20(4):918-957
Let (M,[(g)\tilde]){(\mathcal {M},\tilde{g})} be an N-dimensional smooth compact Riemannian manifold. We consider the singularly perturbed Allen–Cahn equation
e2 D[(g)\tilde] u + (1 - u2 )u = 0 in M,\varepsilon ^2 \Delta _{\tilde g} u \, + \, (1 - u^2 )u\, =\, 0 \quad {\rm{in}} \, \mathcal {M}, 相似文献
11.
Pierre Angl��s 《Advances in Applied Clifford Algebras》2011,21(2):233-246
This self-contained short note deals with the study of the properties of some real projective compact quadrics associated
with a a standard pseudo-hermitian space H
p,q
, namely [(Q(p, q))\tilde], [(Q2p+1,1)\tilde], [(Q1,2q+1)\tilde], [(Hp,q)\tilde]. [(Q(p, q))\tilde]{\widetilde{Q(p, q)}, \widetilde{Q_{2p+1,1}}, \widetilde{Q_{1,2q+1}}, \widetilde{H_{p,q}}. \, \widetilde{Q(p, q)}} is the (2n – 2) real projective quadric diffeomorphic to (S
2p–1 × S
2q–1)/Z
2. inside the real projective space P(E
1), where E
1 is the real 2n-dimensional space subordinate to H
p,q
. The properties of [(Q(p, q))\tilde]{\widetilde{Q(p, q)}} are investigated. [(Hp,q)\tilde]{\widetilde{H_p,q}} is the real (2n – 3)-dimensional compact manifold-(projective quadric)- associated with H
p,q
, inside the complex projective space P(H
p,q
), diffeomorphic to (S
2p–1 × S
2q–1)/S
1. The properties of [(Hp,q)\tilde]{\widetilde{H_{p,q}}} are studied. [(Q2p+1,1)\tilde]{\widetilde{Q_{2p+1,1}}} is a 2p-dimensional standard real projective quadric, and [(Q1,2q+1)\tilde]{\widetilde{Q_{1,2q+1}}} is another standard 2q-dimensional projective quadric. [(Q2p+1,1)\tilde] è[(Q1,2q+1)\tilde]{\widetilde{Q_{2p+1,1}} \cup \widetilde{Q_{1,2q+1}}}, union of two compact quadrics plays a part in the understanding of the "special pseudo-unitary conformal compactification"
of H
p,q
. It is shown how a distribution y → D
y
, where y ? H\{0},H{y \in H\backslash\{0\},H} being the isotropic cone of H
p,q
allows to [(Hp+1,q+1)\tilde]{\widetilde{H_{p+1,q+1}}} to be considered as a "special pseudo-unitary conformal compactified" of H
p,q
× R. The following results precise the presentation given in [1,c]. 相似文献
12.
In Finsler geometry, minimal surfaces with respect to the Busemann-Hausdorff measure and the Holmes-Thompson measure are called
BH-minimal and HT-minimal surfaces, respectively. In this paper, we give the explicit expressions of BH-minimal and HT-minimal
rotational hypersurfaces generated by plane curves rotating around the axis in the direction of
[(b)\tilde]\sharp{\tilde{\beta}^{\sharp}} in Minkowski (α, β)-space
(\mathbbVn+1,[(Fb)\tilde]){(\mathbb{V}^{n+1},\tilde{F_b})} , where
\mathbbVn+1{\mathbb{V}^{n+1}} is an (n+1)-dimensional real vector space, [(Fb)\tilde]=[(a)\tilde]f([(b)\tilde]/[(a)\tilde]), [(a)\tilde]{\tilde{F_b}=\tilde{\alpha}\phi(\tilde{\beta}/\tilde{\alpha}), \tilde{\alpha}} is the Euclidean metric, [(b)\tilde]{\tilde{\beta}} is a one form of constant length
b:=||[(b)\tilde]||[(a)\tilde], [(b)\tilde]\sharp{b:=\|\tilde{\beta}\|_{\tilde{\alpha}}, \tilde{\beta}^{\sharp}} is the dual vector of [(b)\tilde]{\tilde{\beta}} with respect to [(a)\tilde]{\tilde{\alpha}} . As an application, we first give the explicit expressions of the forward complete BH-minimal rotational surfaces generated
around the axis in the direction of
[(b)\tilde]\sharp{\tilde{\beta}^{\sharp}} in Minkowski Randers 3-space
(\mathbbV3,[(a)\tilde]+[(b)\tilde]){(\mathbb{V}^{3},\tilde{\alpha}+\tilde{\beta})} . 相似文献
13.
Jaeman Kim 《Monatshefte für Mathematik》2007,47(1):251-254
We show that every compact Einstein Hermitian surface with constant *–scalar curvature is a K?hler surface. In contrast to
the 4-dimensional case, it is shown that there exists a compact Einstein Hermitian (4n + 2)-dimensional manifold with constant *–scalar curvature which is not K?hler. 相似文献
14.
Craig van Coevering 《Annals of Global Analysis and Geometry》2012,42(3):287-315
Extending the results of Cheng and Yau it is shown that a strictly pseudoconvex domain ${M\subset X}$ in a complex manifold carries a complete K?hler–Einstein metric if and only if its canonical bundle is positive, i.e. admits an Hermitian connection with positive curvature. We consider the restricted case in which the CR structure on ${\partial M}$ is normal. In this case M must be a domain in a resolution of the Sasaki cone over ${\partial M}$ . We give a condition on a normal CR manifold which it cannot satisfy if it is a CR infinity of a K?hler–Einstein manifold. We are able to mostly determine those normal CR three-manifolds which can be CR infinities. We give many examples of K?hler–Einstein strictly pseudoconvex manifolds on bundles and resolutions. In particular, the tubular neighborhood of the zero section of every negative holomorphic vector bundle on a compact complex manifold whose total space satisfies c 1?<?0 admits a complete K?hler–Einstein metric. 相似文献
15.
Misha Verbitsky 《Mathematische Zeitschrift》2010,264(4):939-957
Let (M, ω) be a Kähler manifold. An integrable function ${\varphi}
16.
Craig van Coevering 《Mathematische Annalen》2010,347(3):581-611
We prove that a crepant resolution π : Y → X of a Ricci-flat Kähler cone X admits a complete Ricci-flat Kähler metric asymptotic to the cone metric in every Kähler class in ${H^2_c(Y,\mathbb{R})}
17.
Ameer Athavale 《Integral Equations and Operator Theory》2010,68(2):255-262
We consider an important class of subnormal operator m-tuples M
p
(p = m,m + 1, . . .) that is associated with a class of reproducing kernel Hilbert spaces Hp{{\mathcal H}_p} (with M
m
being the multiplication tuple on the Hardy space of the open unit ball
\mathbb B2m{{\mathbb B}^{2m}} in
\mathbb Cm{{\mathbb C}^m} and M
m+1 being the multiplication tuple on the Bergman space of
\mathbb B2m{{\mathbb B}^{2m}}). Given any two C*-algebras A{\mathcal A} and B{\mathcal B} from the collection {C*(Mp), C*([(M)\tilde]p): p 3 m}{\{C^*({M}_p), C^*({\tilde M}_p): p \geq m\}} , where C*(M
p
) is the unital C*-algebra generated by M
p
and C*([(M)\tilde]p){C^*({\tilde M}_p)} the unital C*-algebra generated by the dual [(M)\tilde]p{{\tilde M}_p} of M
p
, we verify that A{\mathcal A} and B{\mathcal B} are either *-isomorphic or that there is no homotopy equivalence between A{\mathcal A} and B{\mathcal B} . For example, while C*(M
m
) and C*(M
m+1) are well-known to be *-isomorphic, we find that C*([(M)\tilde]m){C^*({\tilde M}_m)} and C*([(M)\tilde]m+1){C^*({\tilde M}_{m+1})} are not even homotopy equivalent; on the other hand, C*(M
m
) and C*([(M)\tilde]m){C^*({\tilde M}_{m})} are indeed *-isomorphic. Our arguments rely on the BDF-theory and K-theory. 相似文献
18.
Jakob Jonsson 《Annals of Combinatorics》2010,14(4):487-505
Let 1 ≤ m ≤ n. We prove various results about the chessboard complex M
m,n
, which is the simplicial complex of matchings in the complete bipartite graph K
m,n
. First, we demonstrate that there is nonvanishing 3-torsion in
[(H)\tilde]d(\sf Mm,n; \mathbb Z){{\tilde{H}_d({\sf M}_{m,n}; {\mathbb Z})}} whenever
\fracm+n-43 £ d £ m-4{{\frac{m+n-4}{3}\leq d \leq m-4}} and whenever 6 ≤ m < n and d = m − 3. Combining this result with theorems due to Friedman and Hanlon and to Shareshian and Wachs, we characterize all triples
(m, n, d ) satisfying
[(H)\tilde]d (\sf Mm,n; \mathbb Z) 1 0{{\tilde{H}_d \left({\sf M}_{m,n}; {\mathbb Z}\right) \neq 0}}. Second, for each k ≥ 0, we show that there is a polynomial f
k
(a, b) of degree 3k such that the dimension of
[(H)\tilde]k+a+2b-2 (\sf Mk+a+3b-1,k+2a+3b-1; \mathbb Z3){{\tilde{H}_{k+a+2b-2}}\,\left({{\sf M}_{k+a+3b-1,k+2a+3b-1}}; \mathbb Z_{3}\right)}, viewed as a vector space over
\mathbbZ3{\mathbb{Z}_3}, is at most f
k
(a, b) for all a ≥ 0 and b ≥ k + 2. Third, we give a computer-free proof that
[(H)\tilde]2 (\sf M5,5; \mathbb Z) @ \mathbb Z3{{\tilde{H}_2 ({\sf M}_{5,5}; \mathbb {Z})\cong \mathbb Z_{3}}}. Several proofs are based on a new long exact sequence relating the homology of a certain subcomplex of M
m,n
to the homology of M
m-2,n-1 and M
m-2,n-3. 相似文献
19.
Jaeman Kim 《Monatshefte für Mathematik》2007,152(3):251-254
We show that every compact Einstein Hermitian surface with constant *–scalar curvature is a K?hler surface. In contrast to
the 4-dimensional case, it is shown that there exists a compact Einstein Hermitian (4n + 2)-dimensional manifold with constant *–scalar curvature which is not K?hler.
This study is supported by Kangwon National University. 相似文献
20.
Lawrence A. Fialkow 《Integral Equations and Operator Theory》2003,45(4):405-435
We solve the truncated complex moment problem for measures supported on the variety K o \mathcal{K}\equiv { z ? \in C: z [(z)\tilde]\widetilde{z} = A+Bz+C [(z)\tilde]\widetilde{z} +Dz 2 ,D 1 \neq 0}. Given a doubly indexed finite sequence of complex numbers g o g(2n):g00,g01,g10,?,g0,2n,g1,2n-1,?,g2n-1,1,g2n,0 \gamma\equiv\gamma^{(2n)}:\gamma_{00},\gamma_{01},\gamma_{10},\ldots,\gamma_{0,2n},\gamma_{1,2n-1},\ldots,\gamma_{2n-1,1},\gamma_{2n,0} , there exists a positive Borel measure m\mu supported in K \mathcal{K} such that gij=ò[`(z)]izj dm (0 £ 1+j £ 2n) \gamma_{ij}=\int\overline{z}^{i}z^{j}\,d\mu\,(0\leq1+j\leq2n) if and only if the moment matrix M(n)( g\gamma ) is positive, recursively generated, with a column dependence relation Z [(Z)\tilde]\widetilde{Z} = A1+BZ +C [(Z)\tilde]\widetilde{Z} +DZ 2, and card V(g) 3\mathcal{V}(\gamma)\geq rank M(n), where V(g)\mathcal{V}(\gamma) is the variety associated to g \gamma . The last condition may be replaced by the condition that there exists a complex number gn,n+1 \gamma_{n,n+1} satisfying gn+1,n o [`(g)]n,n+1=Agn,n-1+Bgn,n+Cgn+1,n-1+Dgn,n+1 \gamma_{n+1,n}\equiv\overline{\gamma}_{n,n+1}=A\gamma_{n,n-1}+B\gamma_{n,n}+C\gamma_{n+1,n-1}+D\gamma_{n,n+1} . We combine these results with a recent theorem of J. Stochel to solve the full complex moment problem for K \mathcal{K} , and we illustrate the connection between the truncated and full moment problems for other varieties as well, including the variety z k = p(z, [(Z)\tilde] \widetilde{Z} ), deg p < k. 相似文献
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