论文标题
在表面和Borsuk-Ulam定理上进行自由循环作用
Free cyclic actions on surfaces and the Borsuk-Ulam theorem
论文作者
论文摘要
令$ m $和$ n $为拓扑空间,让$ g $为一个组,让$τ\ colon \ thinspace g \ times m \ to m $是$ g $的适当免费操作。在本文中,我们定义了与对$ $(g,τ)$相对于$ m $到$ n $的同质地图类别的Borsuk-ulam型属性,该属性从$ n $ n $ n $ -sphere $ \ mathbb {s}^n $ to $ n $ to $ n $ \ n $ to $ n $ n $ n $ from $ n $ n $ n $ \ n $ n $ n $ n.如果$ m $是有限的路线连接的有限的CW-复合物,则$ g $是有限的,非繁琐的Abelian组,$τ$是一种适当的免费蜂窝动作,而$ n $是$ \ mathbb {r}^2 $或一个紧凑型表面,而没有$ \ m native $ \ mathbb {$ \ mathbb {2 $ {2 $ {2 $ {代数标准涉及编织组,以决定[m,n] $中的自由同型$β\是否具有Borsuk-ulam属性。作为此标准的应用,我们考虑了$ m $是一个紧凑的表面的情况,没有边界,配备有限循环组$ \ mathbb {z} _n $的免费动作$τ$。就操作$τ$的轨道空间$m_τ$的可定位性而言$(\ mathbb {z} _n,τ)$。最后,我们给出了一些表面的示例,在这些表面上,对称组的行为,对于这些情况,我们获得了有关borsuk-ulam属性的部分结果,其目标为$ \ mathbb {r}^2 $。
Let $M$ and $N$ be topological spaces, let $G$ be a group, and let $τ\colon\thinspace G \times M \to M$ be a proper free action of $G$. In this paper, we define a Borsuk-Ulam-type property for homotopy classes of maps from $M$ to $N$ with respect to the pair $(G,τ)$ that generalises the classical antipodal Borsuk-Ulam theorem of maps from the $n$-sphere $\mathbb{S}^n$ to $\mathbb{R}^n$. In the cases where $M$ is a finite pathwise-connected CW-complex, $G$ is a finite, non-trivial Abelian group, $τ$ is a proper free cellular action, and $N$ is either $\mathbb{R}^2$ or a compact surface without boundary different of $\mathbb{S}^2$ and $\mathbb{RP}^2$, we give an algebraic criterion involving braid groups to decide whether a free homotopy class $β\in [M,N]$ has the Borsuk-Ulam property. As an application of this criterion, we consider the case where $M$ is a compact surface without boundary equipped with a free action $τ$ of the finite cyclic group $\mathbb{Z}_n$. In terms of the orientability of the orbit space $M_τ$ of $M$ by the action $τ$, the value of $n$ modulo $4$ and a certain algebraic condition involving the first homology group of $M_τ$, we are able to determine if the single homotopy class of maps from $M$ to $\mathbb{R}^2$ possesses the Borsuk-Ulam property with respect to $(\mathbb{Z}_n,τ)$. Finally, we give some examples of surfaces on which the symmetric group acts, and for these cases, we obtain some partial results regarding the Borsuk-Ulam property for maps whose target is $\mathbb{R}^2$.