共查询到19条相似文献,搜索用时 46 毫秒
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Wei-jun Lu 《高校应用数学学报(英文版)》2013,28(2):240-252
In this paper, we study f-harmonicity of some special maps from or into a doubly warped product manifold. First we recall some properties of doubly twisted product manifolds. After showing that the inclusion maps from Riemannian manifolds M and N into the doubly warped product manifold M × μ,λ N can not be proper f-harmonic maps, we use projection maps and product maps to construct nontrivial f-harmonic maps. Thus we obtain some similar results given in [21], such as the conditions for f-harmonicity of projection maps and some characterizations for non-trivial f-harmonicity of the special product maps. Furthermore, we investigate non-trivial f-harmonicity of the product of two harmonic maps. 相似文献
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Wei ZHU 《数学年刊B辑(英文版)》2012,33(4):595-600
The author studies the regularity of energy minimizing maps from Finsler manifolds to Riemannian manifolds.It is also shown that the energy minimizing maps are smooth,when the target manifolds have no ... 相似文献
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Chaohui ZHANG 《数学年刊B辑(英文版)》2011,32(6):885-894
Let S be a Riemann surface that contains one puncture x. Let ℐ be the collection of simple closed geodesics on S, and let ℱ denote the set of mapping classes on S isotopic to the identity on S ∪ {x}. Denote by t c the positive Dehn twist about a curve c ∈ ℐ. In this paper, the author studies the products of forms (t b −m ∘ t a n ) ∘ f k , where a, b ∈ ℐ and f ∈ ℱ. It is easy to see that if a = b or a, b are boundary components of an x-punctured cylinder on S, then one may find an element f ∈ ℱ such that the sequence (t b −m ∘ t n a ) ∘ f k contains infinitely many powers of Dehn twists. The author shows that the converse statement remains true, that is, if the sequence (t b −m ∘ t a n ) ∘ f k contains infinitely many powers of Dehn twists, then a, b must be the boundary components of an x-punctured cylinder on S and f is a power of the spin map t b −1 ∘ t a . 相似文献
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Rodin and Sullivan (1987) proved Thurston's conjecture that a scheme based on the Circle Packing Theorem converges to the Riemann mapping, thereby proved a refreshing geometric view of the Riemann Mapping Theorem. Naturally, we consider to use the ellipses to pack the bounded simply connected domain and obtain similarly a sequence simplicial homeomorphism between the ellipse packing and the circle packing. In this paper, we prove that these simplicial homeomorphism approximate a quasiconformal mapping from the bounded simply connected domain onto the unit disk with the modulus of their complex dilatations tending to 1 almost everywhere in the domain when the ratio of the longer axis and shorter axis of the ellipse tending to ∞. 相似文献
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51. IntroductionAn importallt problem in memannian geometry is whether the manifold is of finite topological type. By it we mean that there is a compact domain fi C M such that M C fi ishomeomorphic to off x [0, co). If the manifold has nonnegative Ricci curvature, some important results have been obtained by mathematicans (see [1,3,4,5,6, etc.]). It is well knownthat if Ric(M)20, one has Gromvo-Bishop volume comparison theorem and for any givenPPM, r > 0,c(n)vol[B(P, 1)]rsvol[B(p, r)]sw… 相似文献
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The Energy Growth Property for Harmonic MapsTheEnergyGrowthPropertyforHarmonicMaps¥LiHongyi;ZhaoDi(NorthChinainstituteofWater... 相似文献
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本文研究了具有非负Ricci曲率和次大体积增长的完备黎曼流形的拓扑结构问题.利用Toponogov型比较定理及临界点理论,获得了流形具有有限拓扑型的结果,推广了H.Zhan和Z.Shen的定理,并且还证明了该流形的基本群是有限生成的. 相似文献
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Chaohui ZHANG? 《数学年刊B辑(英文版)》2008,29(1):85-94
It is well known that certain isotopy classes of oseudo-Anosov maos on a Riemann surface S of non-excluded type can be defined through Dehn twists tα and tβ along simple closed geodesics α and β on S,respectively. Let G be the corresponding Fuchsian group acting on the hyperbolic plane H so that H/G≌S.For any point α∈S,define S = S/{α}.In this article, the author gives explicit parabolic elements of G from which he constructs pseudo-Anosov classes on S that can be projected to a given pseudo-Anosov class on S obtained from Thurston's construction. 相似文献
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Chaohui ZHANG 《数学年刊B辑(英文版)》2007,28(1):55-66
Let S be a Riemann surface with genus p and n punctures. Assume that 3p - 3 n > 0 and n ≥ 1. Let a be a puncture of S and let (~S) = S ∪ {a}. Then all mapping classes in the mapping class group Mods that fixes the puncture a can be projected to mapping classes of Mod(~S) under the forgetful map. In this paper the author studies the mapping classes in Mods that can be projected to a given hyperbolic mapping class in Mod(~S). 相似文献
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The main result of this paper is a universal finiteness theorem for the set of all small dilatation pseudo-Anosov homeomorphisms ?:S→S, ranging over all surfaces S. More precisely, we consider pseudo-Anosov homeomorphisms ?:S→S with |χ(S)|log(λ(?)) bounded above by some constant, and we prove that, after puncturing the surfaces at the singular points of the stable foliations, the resulting set of mapping tori is finite. Said differently, there is a finite set of fibered hyperbolic 3-manifolds so that all small dilatation pseudo-Anosov homeomorphisms occur as the monodromy of a Dehn filling on one of the 3-manifolds in the finite list, where the filling is on the boundary slope of a fiber. 相似文献
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Richard Brown 《Geometriae Dedicata》2003,97(1):129-150
In this note, we show that given a closed, orientable genus-g surface S
g
, any hyperbolic toral automorphism has a positive power which induces a quadratic, orientable pseudo-Anosov homeomorphism on S
g
. To show this, we lift Anosov toral automorphisms through a ramified topological covering and present the lifted homeomorphism via a standard set of Lickorish twists. This construction provides a general method of producing pseudo-Anosov maps of closed surfaces with predetermined orientable foliations and quadratic dilatation. Since these lifted automorphisms have orientable foliations, this construction is a sort of converse to that of Franks and Rykken [Trans. Amer. Math. Soc. 1999], who established that one can associate to a quadratic pseudo-Anosov homeomorphism with oriented unstable foliation a hyperbolic toral automorphism. 相似文献
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Yoshiko Sakata Mitsuyuki Ochiai Kayo Satoh 《Proceedings of the American Mathematical Society》2001,129(2):559-566
We will give a very simple algorithm to decompose a gluing homeomorphism of a planar Heegaard diagram of genus two into Dehn twists associated with the canonical base.
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CAI Yongmao & SHEN Yuliang Department of Mathematics Suzhou University Suzhou China 《中国科学A辑(英文版)》2006,(5)
It is proved that for any Fuchsian group Г such that H/Г is a hyperbolic Riemann surface, the Teichmuller curve V(Г) has a unique complex manifold structure so that the natural projection of the Bers fiber space F(Г) onto V(Г) is holomorphic with local holomorphic sections. An isomorphism theorem for Teichmuller curves is deduced, which generalizes a classical result that the Teichmuller curve V(Г) depends only on the type of Г and not on the orders of the elliptic elements of Г when H/Г is a compact hyperbolic Riemann surface. 相似文献