In this paper, we give a weak classification of locally linear pseudofree actions of the cyclic group of order 3 on a $K3$ surface, and prove the existence of such an action which can not be realized as a smooth action on the standard smooth $K3$ surface.
R. S. Kulkarni表明,一个有限群的作用伪自由,但不自由,保持方向,在一个偶数维领域(或适当的球形空间)要么是一个周期群半自由地与两个不动点,一个二面体群与三个奇异轨道,或一个多面体群,只发生在2维。本文证明了当n全等于0 mod 4时,二面体群在实际n-球面上不是伪自由的和局部线性的作用。当n等于2 mod 4且n>2时,这种作用的可能性仍然是开放的。还考虑了方向反转动作。
回想一下,空间上的伪自由群作用是其奇异集仅由孤立点组成的作用。本文对S^2 × S^2上所有允许伪自由作用的有限群进行了分类。这些群恰好是我们所期望的群:它们允许S^2 x S^2上的正交伪自由作用作为R^3 x R^3的子集。它们被明确列出。这篇论文可以被看作是Edmonds,math.GT/9809055论文的姊妹篇。
There are four groups $G$ fitting into a short exact sequence $ 1\rightarrow SL(2,5)\rightarrow G\rightarrow C_2\rightarrow 1, $ where $SL(2,5)$ is the special linear group of $(2\times 2)$-matrices with entries in the field of five elements. Except for the direct product of $SL(2,5)$ and $C_2$, there are two other semidirect products of these two groups and just one non-semidirect product $SL(2,5).C_2$, considered in this paper. It is known that each finite nonsolvable group can act on spheres with arbitrary positive number of fixed points. Clearly, $SL(2,5).C_2$ is a nonsolvable group. Moreo…
证明了秩为2的有限交换群阿贝尔群上的局部线性同调平凡作用的单连通四流形同胚于CP ^2,-CP ^2和S ^2 x S ^2的连通和(有一个例外:Chern流形上的伪自由Z_3 x Z_3作用),并建立了一个等变分解定理.这推广了1970年Orlik和Raymond的论文中的结果,并补充了Fintushel、Yoshida和Huck最近关于S^1作用量的工作。在每种情况下,支持这种作用的单连通四维流形基本上是相同的。
We obtain representations of the f-based Mapping Class Group of oriented punctured surfaces from an action of mapping classes on Heisenberg homologies of a circle bundle over surface configurations.
The classification of finite group-actions on closed surfaces of small genus is well-known. In the present paper we are interested in the question of which of these group-actions are bounding (extend to a compact 3-manifold with the surface as its unique boundary component, e.g. to a handlebody) or geometrically bounding (extend to a hyperbolic 3-manifold with totally geodesic boundary), concentrating, as a typical case, on large group-actions on surfaces of genus 3.
The present work introduces new perspectives in order to extend finite group actions from surfaces to 3-manifolds. We consider the Schur multiplier associated to a finite group $G$ in terms of principal $G$-bordisms in dimension two, called $G$-cobordisms. We are interested in the question of when a free action of a finite group on a closed oriented surface extends to a non-necessarily free action on a 3-manifold. We show the answer to this question is affirmative for abelian, dihedral, symmetric and alternating groups. As an application of our methods, we show that every non-necessarily free …
We construct the Fukaya category of a surface with genus greater than one and compute its Grothendieck group. We consider here a topological variant, in which we disregard the area form and use instead an admissibility condition borrowed from Heegaard-Floer theory which ensures invariance under isotopy. We also study action of the mapping class group of the surface on its Fukaya category and establish faithfulness.
We provide the first known example of a finite group action on an oriented surface $T$ that is free, orientation-preserving, and does not extend to an arbitrary (in particular, possibly non-free) orientation-preserving action on any compact oriented 3-manifold $N$ with boundary $\partial N = T$. This implies a negative solution to a conjecture of Domínguez and Segovia, as well as Uribe's evenness conjecture for equivariant unitary bordism groups. We more generally provide sufficient conditions that imply infinitely many such group actions on surfaces exist. Intriguingly, any group with such a …
We let the mapping class group $Γ_{g,1}$ of a genus $g$ surface $Σ_{g,1}$ with one boundary component act on the homology $H_*(F_{n}(Σ_{g,1});\mathbb{Q})$ of the $n^{th}$ ordered configuration space of the surface. We prove that the action is non-trivial when restricted to the $(n-1)^{st}$ stage of the Johnson filtration, for all $n\ge 1$ and $g\ge 2$. We deduce an analogous result for closed surfaces.