Kodai Mathematical Journal

Curvature characterizations of twistor spaces over four-dimensional Riemannian manifolds

Brendan Foreman

2002 年 25 巻 3 号 p. 167-190
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674453

ジャーナルフリー

抄録を表示する抄録を非表示にする

In this paper, we study the complex contact structure of a twistor space over a self-dual, Einstein 4-manifold with nonzero scalar curvature. Although the existence of such a structure has been known and well utilized by researchers for several decades now, the Hermitian geometry resulting from the complex contact structure is still in the process of being fully developed. Here we give a characterization of such twistor spaces as those satisfying a curvature (and hence purely geometric) identity. Later, we describe how this result fits in with other areas of research in complex contact geometry.

抄録全体を表示

PDF形式でダウンロード (173K)
Integral means for the n'th derivative of Blaschke products

Mirwan Amin Kutbi

2002 年 25 巻 3 号 p. 191-208
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674454

ジャーナルフリー

PDF形式でダウンロード (153K)
Minimal H₃ actions and simple quotients of discrete 7-dimensional nilpotent groups

Paul Milnes

2002 年 25 巻 3 号 p. 209-226
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674455

ジャーナルフリー

抄録を表示する抄録を非表示にする

For connected nilpotent groups, 7 is the lowest dimension where there are infinitely many non-isomorphic groups, and also where some groups have no discrete cocompact subgroups. Here one infinite family of 7-dimensional connected groups is studied, discrete cocompact subgroups H are found for some of them, and then the faithful simple quotients A of C^*(H) are identified. Such A are shown to be isomorphic to C^*-crossed products C^*(H₃, \mathscr{C}(T³)) generated by some intriguing effective minimal distal flows (H₃, T³), where H₃ is the discrete 3-dimensional Heisenberg group.

抄録全体を表示

PDF形式でダウンロード (162K)
A note on a unicity theorem of K. Tohge

Xiao-Min Li, Hong-Xun Yi

2002 年 25 巻 3 号 p. 227-239
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674456

ジャーナルフリー

抄録を表示する抄録を非表示にする

In this paper, we deal with the problem of uniqueness of meromorphic functions sharing three values CM, and get rid of the restriction on the hyper-orders in a unicity theorem of K. Tohge. An example is provided to show that the result in this paper is best possible.

抄録全体を表示

PDF形式でダウンロード (102K)
Growth of solutions of an n-th order linear differential equation with entire coefficients

Benharrat Belaidi, Saada Hamouda

2002 年 25 巻 3 号 p. 240-245
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674457

ジャーナルフリー

抄録を表示する抄録を非表示にする

We consider a differential equation f⁽ⁿ⁾+A_n−1(z)f⁽ⁿ⁻¹⁾+…+A₁(z)f'+A₀(z)f=0, where A₀(z), ..., A_n−1(z) are entire functions with A₀(z){¬≡}0. Suppose that there exist a positive number μ, and a sequence (z_j)_j∈N with lim_j→+∞z_j=∞, and also two real numbers α, β (0≤β<α) such that |A₀(z_j)|≥e^α|z_j|μ and |A_k(z_j)|≤e^β|z_j|μ as j→+∞ (k=1, ..., n−1). We prove that all solutions f{¬≡}0 of this equation are of infinite order. This result is a generalization of one theorem of Gundersen ([3], p. 418).

抄録全体を表示

PDF形式でダウンロード (72K)
On the overdetermined system about surfaces with parallel mean curvature vector field

Shinya Hirakawa

2002 年 25 巻 3 号 p. 246-253
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674458

ジャーナルフリー

PDF形式でダウンロード (82K)
A remark on systems of differential equations associated with representations of \mathfrak{sl}₂(R) and their perturbations

Alberto Parmeggiani, Masato Wakayama

2002 年 25 巻 3 号 p. 254-277
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674459

ジャーナルフリー

抄録を表示する抄録を非表示にする

We give here a number of examples of non-commutative harmonic oscillators “in disguise” that can be exactly solved by using the tensor product of the oscillator representation and the finite dimensional representation of \mathfrak{sl}(R), and its perturbations

抄録全体を表示

PDF形式でダウンロード (221K)
Certain continued fraction representaions for functions associated with mock theta functions of order three

Anand Kumar Srivastava

2002 年 25 巻 3 号 p. 278-287
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674460

ジャーナルフリー

PDF形式でダウンロード (91K)
A family of polynomials with the uniqueness property for linearly non-degenerate holomorphic mappings

Manabu Shirosaki

2002 年 25 巻 3 号 p. 288-292
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674461

ジャーナルフリー

PDF形式でダウンロード (69K)
On globally minimal foliation with respect to lagrangians on Riemannian manifolds

Tran Viet Dung

2002 年 25 巻 3 号 p. 293-300
発行日: 2002年
公開日: 2009/01/21

DOIhttps://doi.org/10.2996/kmj/1071674462

ジャーナルフリー

PDF形式でダウンロード (85K)
A local limit theorem for random walk defined on a finite Markov chain with absorbing barriers

Toshiyuki Takenami, Michio Shimura

2002 年 25 巻 3 号 p. 301-308
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674463

ジャーナルフリー

抄録を表示する抄録を非表示にする

Let {ξ_n}_n≥0 denote an ergodic Markov chain with a finite state space Ξ={1, 2, ..., s}. For each j, k∈Ξ, let {Y_n^jk}_n≥1 be a sequence of i.i.d. {−1, 1}-valued random variables which are independent of {ξ_n}. We define the process {S_n}_{n≥ 0} by S₀=0 and S_n=S_n−1+Y_n^ξ_n−1ξ_n for n≥ 1. Let a be a positive integer. We denote by T_x the first exit time of the process from the interval [−x, a−x] for each x=0, 1, ..., a. We give an asymptotic behaviour of the transition functions P_jk⁽ⁿ⁾(x, y)=P{x+S_n=y; T_x>n; ξ_n=k|ξ₀=j} as n→∞ for each x, y∈[0, a] and all j, k∈Ξ.

抄録全体を表示

PDF形式でダウンロード (88K)
Uniqueness of entire functions and fixed points

Jianming Chang, Mingliang Fang

2002 年 25 巻 3 号 p. 309-320
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674464

ジャーナルフリー

抄録を表示する抄録を非表示にする

Let f be a nonconstant entire function. If f, f' and f'' have the same fixed points, then f≡f'.

抄録全体を表示

PDF形式でダウンロード (92K)
Darboux transformations and isometric immersions of Riemannian products of space forms

Qun He, Yi-Bing Shen

2002 年 25 巻 3 号 p. 321-340
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674465

ジャーナルフリー

抄録を表示する抄録を非表示にする

By using the Darboux transformation in Soliton theory, we give the explicit construction for local isometric immersions of the Riemannian product M₁^n₁(c₁)×M₂^n₂(c₂) into space forms M^m(c) with flat normal bundle via purely algebraic algorithm.

抄録全体を表示

PDF形式でダウンロード (185K)
Affine submanifolds and the Theorem of Cartan-Ambrose-Hicks

Knut Pawel, Helmut Reckziegel

2002 年 25 巻 3 号 p. 341-356
発行日: 2002年
公開日: 2009/04/24

DOIhttps://doi.org/10.2996/kmj/1071674466

ジャーナルフリー

抄録を表示する抄録を非表示にする

In this article E. Cartan's theorem about the existence of (local) totally geodesic submanifolds with a prescribed tangent plane is generalized to manifolds which are equipped only with a linear connection; there is also given a global version of the theorem. The results are used for a short and geometric proof of the Theorem of Cartan-Ambrose-Hicks, and more generally of a generalization which is concerned with the existence of affine maps of arbitrary rank.

抄録全体を表示

PDF形式でダウンロード (163K)

J-STAGEへの登録はこちら（無料）