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1.
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
2.
H. R. Ebrahimi-Vishki M. A. Pourabdollah 《Proceedings of the American Mathematical Society》1997,125(7):2171-2174
The purpose of this paper is to introduce an algebra of functions on a semitopological semigroup and to study these functions from the point of view of universal semigroup compactification. We show that the corresponding semigroup compactification of this algebra is universal with respect to the property of being a nilpotent group.
3.
通过在一个积分算子上运用Schauder不动点定理,Chirka对Slokowski的全纯运动扩张定理提供了一个优美的简单证明.本文中,作者对构造此证明的启发提供一个参考同时用此方法通过不同方式来构造全纯扩张.一个自然的问题是研究这些用不同方式得到的全纯扩张是否相同.因此对全纯扩张唯一性已有的判断法提供一个简单的综述.最后介绍在全纯扩张唯一性存在时的一个应用. 相似文献
4.
5.
Janina A. Brenner Sándor P. Fekete Jan C. van der Veen 《Mathematical Methods of Operations Research》2009,69(2):281-296
We consider a special case of the directed subgraph homeomorphism or topological minor problem, where the host graph has a
specific regular structure. Given an acyclic directed pattern graph, we are looking for a host graph of minimal height which
still allows for an embedding. This problem has applications in compiler design for certain coarse-grain reconfigurable architectures.
In this application domain, the task is to simultaneously schedule, bind and route a so-called data-flow graph, where vertices represent operations and arcs stand for data dependencies between the operations, given an orthogonal
grid structure of reconfigurable processing elements (PEs) that have restricted communication abilities. We show that the
problem of simultaneously scheduling, binding and routing is NP-complete by describing a logic engine reduction from NAE-3-SAT.
This result holds even when the input graph is a directed tree with maximum indegree two. We also give a |V|3/2-approximation algorithm.
J. A. Brenner’s research supported by the DFG Research Center Matheon “Mathematics for key technologies”.
J. C. van der Veen’s research supported by DFG Focus Program 1148, “Reconfigurable Architectures”, Grants FE 407/8-1 and FE
407/8-2. 相似文献
6.
L. A. Beklaryan 《Mathematical Notes》2002,71(3-4):305-315
In [1] G. Margulis proved Ghys's conjecture stating the validity of the following analog of the Tits alternative: either the group
of homeomorphisms of the circle possesses a free subgroup with two generators or there is an invariant probabilistic measure on S
1
. In the present paper, we prove the following strengthening of Margulis's statement: an invariant probabilistic measure for a group
exists if and only if the quotient group
does not contain a free subgroup with two generators (here
is some specific subgroup of G defined in a canonical way). We also formulate and prove analogs of the Tits alternative for groups
of homeomorphisms of the line. 相似文献
7.
8.
Ronny Nahum 《Proceedings of the American Mathematical Society》2001,129(7):1995-1999
For every normed space , we note its closed unit ball and unit sphere by and , respectively. Let and be normed spaces such that is Lipschitz homeomorphic to , and is Lipschitz homeomorphic to .
We prove that the following are equivalent:
1. is Lipschitz homeomorphic to .
2. is Lipschitz homeomorphic to .
3. is Lipschitz homeomorphic to .
This result holds also in the uniform category, except (2 or 3) 1 which is known to be false.
9.
SHEN Yuliang 《中国科学A辑(英文版)》2000,43(9):929-936
Given a quasisymmetric homeomorphismh of the unit circle onto itself, denote byK
n
*
,H
h
andK
h
the extremal maximal dilatation, boundary dilatation and maximal dilatation ofh, respectively. It is proved that there exists a family of quasisymmetric homeomorphismsh such thatK
h
<H
h
=K
h
*
This gives a negative answer to a problem asked independently by Wu and Yang. Furthermore, some related topics are also discussed. 相似文献
10.
非线性伪抛物方程由于其来源于一些重要的物理过程而成为研究热点.对于一类三阶非线性伪抛物方程的初边值问题,给出了Hilbert空间中相应的强制不等式,利用同胚理论及推广的反函数定理,得到了非线性方程初边值问题解的大范围存在定理.对于相应的半线性方程给出了初边值问题解的大范围存在性、唯一性定理. 相似文献