离散动力系统水动点类的Nielsen数

本文在［１］，［３］的基础上引入了离散动力系统不动点类的Ｎｉｅｌｓｅｎ－数，讨论了Ｎｉｅｌｓｅｎ－数的同伦性质，得到利用Ｎｉｅｌｅｓｎ－数估计离散动力系统不动点个数的几个结果，为进一步研究该系统不动点的个数问题提供了有用的工具。     

离散动力系统不动点类的Nielsen数

本文在[1],[3]的基础上引入了离散动力系统不动点类的Nielsen-数,讨论了Nielsen-数的同伦性质,得到利用Nielesn-数估计离散动力系统不动点个数的几个结果,为地一步研究该系统不动点的个数问题提供了有用的工具。     

向量场的Nielsen数

对于紧致流形M上的任意一个向量场X，定义了一个由向量场X确定的自映射fX：M→M，使得向量场X的奇异点均为fX的不动点．证明了向量场的Nielsen数是不依赖于向量场选取的量．     

不动点在讨论驻点存在性问题中的应用

本文通过建立不动点与驻点之间的关系，从而利用不动点的存在性来确定函数驻点的存在性。     

闭轨线上模映射的不动点类与拓扑熵下界估计

本文在自治系统dx/dt=f(x),f∈C(DRn,Rn)的闭轨线Γ上定义了模映射,并利用闭轨线Γ与单位圆周S1的同胚关系,给出了模映射的Reidemeister数、Nielsen数,以及模映射的拓扑熵下界估计.     

三维幂零流形上映射的 Nielsen 型数和同伦最小周期集

对于三维幂零流形上的所有映射, 给出了完整计算 Nielsen 型数 $NP_n(f)$ 和 $N\Phi_n(f)$ 的显式公式. 最一般的情形已被 Heath 和 Keppelmann 讨论过, 我们研究剩余的部分. 而在三维幂零流形映射的同伦最小周期集的研究中, 给出了三维幂零流形上所有映射的最小周期集的完整描述, 并包含了对Jezierski和Marzantowicz 结果的改正.     

离散动力系统不动点类的Reidemeister数

本文在[1]的基础上进一步研究了离散系统f的不动点分类问题,并由此得到了该系统不动点类的同伦不变量—Reidemeister数R(f)。定义1.设(X,p)是X的一个覆叠空间,而X是单连通的。若(X’,p’)是X的任一覆叠空间,则应存在一个从(X,p)到(X’,p’)的同态φ,且易知(X,φ)是X’的一     

两个空间之间复合映射的不动点集和Reidemeister数

设X,Y为拓扑空间,f:X--> Y, g:Y--> X.该文证明了下列结论：对每一自然数n,(1)f(Fix((g f)^n))=Fix((f g)^n), g(Fix((f g)^n))=Fix((g f)^n),且#Fix((g f)^n)=#Fix((f g)^n);(2)R((g f)^n)=R((f g)^n).     

两个空间之间复合映射的不动点集和Reidemeister数

设X,Y为拓扑空间,f:X→Y,g:y→X．该文证明了下列结论:对每一自然数n, (1)f(Fix((g o,f)n))=Fix((f o g)n),g(Fix((f og )n))=Fix(g o f)n),且#Fix((g o f)n)= #Fix((f o g)n);(2)R((g o f)n)=R((f o g)n)．     

一种新的变维数不动点算法

本文提出计算标准单纯形S″上连续自映射不动点的一种变维数重复开始不动点算法,证明了算法的可行性和有限步收敛性.一些数值试验结果表明新的不动点算法可以与三明治算法相媲美。     

Computation of Nielsen numbers for maps of closed surfaces

Let be a closed surface, and let be a map. We would like to determine Nielsen fixed point theory provides a lower bound for , called the Nielsen number, which is easy to define geometrically and is difficult to compute.

We improve upon an algebraic method of calculating developed by Fadell and Husseini, so that the method becomes algorithmic for orientable closed surfaces up to the distinguishing of Reidemeister orbits. Our improvement makes tractable calculations of Nielsen numbers for many maps on surfaces of negative Euler characteristic. We apply the improved method to self-maps on the connected sum of two tori including classes of examples for which no other method is known. We also include the application of this algebraic method to maps on the Klein bottle . Nielsen numbers for maps on were first calculated (geometrically) by Halpern. We include a sketch of Halpern's never published proof that for all maps on .

     

Nielsen fixed point theory for partially ordered sets

In this paper, we introduce a Nielsen type number for any selfmap f of a partially ordered set of spaces. This Nielsen theory relates to various existing Nielsen type fixed point theories for different settings such as maps of pairs of spaces, maps of triads, fibre preserving maps, equivariant maps and iterates of maps, by exploring their underlying poset structures.     

A generalized Nielsen number and multiplicity results for differential inclusions

The Nielsen number is defined for a rather general class of multivalued maps on compact connected ANRs, including, e.g., admissible maps (in the sense of Górniewicz (1976); compare also Górniewicz (1995)) on tori. Since the Poincaré maps generated by the Marchaud vector fields are of this type (see (Andres, 1997)), we can obtain in such a way multiplicity results for differential inclusions. More precisely, the nontrivial Nielsen number gives a lower estimate of coincidence points (in particular, fixed points) corresponding to the desired solutions.     

Some developments in Nielsen fixed point theory

We give a brief survey of some developments in Nielsen fixed point theory. After a look at early history and a digress to various generalizations, we confine ourselves to several topics on fixed points of self-maps on manifolds and polyhedra. Special attention is paid to connections with geometric group theory and dynamics, as well as some formal approaches.     

Least number of periodic points of self-maps of Lie groups

There are two algebraic lower bounds of the number of n-periodic points of a self-map f :M → M of a compact smooth manifold of dimension at least 3:N Fn(f) = min{#Fix(gn); g ～f; g is continuous} and N J Dn(f) = min{#Fix(gn); g ～ f; g is smooth}.In general,N J Dn(f) may be much greater than N Fn(f).If M is a torus,then the invariants are equal.We show that for a self-map of a nonabelian compact Lie group,with free fundamental group,the equality holds  all eigenvalues of a quotient cohomology homomorphism induced by f have moduli ≤ 1.     

Fixed point theorems for better admissible multimaps on abstract convex spaces

In this paper, a better admissible class B+ is introduced and a new fixed point theorem for better admissible multimap is proved on abstract convex spaces. As a consequence, we deduce a new fixed point theorem on abstract convex Φ-spaces. Our main results generalize some recent work due to Lassonde, Kakutani, Browder, and Park.     

Nielsen numbers of n-valued fiber maps

The Nielsen number for n-valued multimaps, defined by Schirmer, has been calculated only for the circle. A concept of n-valued fiber map on the total space of a fibration is introduced. A formula for the Nielsen numbers of n-valued fiber maps of fibrations over the circle reduces the calculation to the computation of Nielsen numbers of single-valued maps. If the fibration is orientable, the product formula for single-valued fiber maps fails to generalize, but a “semi-product formula" is obtained. In this way, the class of n-valued multimaps for which the Nielsen number can be computed is substantially enlarged. Dedicated, with gratitude, to Felix Browder who, long ago, encouraged and supported a young topologist’s interest in fixed point theory