Free Cyclic Actions on Surfaces and the Borsuk-Ulam Theorem

Author(s)

Goncalves, Daciberg Lima ; Guaschi, John ; Laass, Vinicius Casteluber

• Document type: Journal article
• Source: Acta Mathematica Sinica - English Series; v. 38, n. 10, p. 20-pg., 2022-10-01.

Abstract

Let M and N be topological spaces, let G be a group, and let tau : GxM -> 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, tau) that generalises the classical antipodal Borsuk-Ulam theorem of maps from the n-sphere S-n to R-n. In the cases where M is a finite pathwise-connected CW-complex, G is a finite, non-trivial Abelian group, tau is a proper free cellular action, and N is either R-2 or a compact surface without boundary different from S-2 and RP2, we give an algebraic criterion involving braid groups to decide whether a free homotopy class beta is an element of [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 tau of the finite cyclic group Z(n). In terms of the orientability of the orbit space M-tau of M by the action tau, the value of n modulo 4 and a certain algebraic condition involving the first homology group of M-tau, we are able to determine if the single homotopy class of maps from M to R-2 possesses the Borsuk-Ulam property with respect to (Z(n), tau). 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 R-2. (AU)

• FAPESP's process: 16/24707-4 - Algebraic, geometric and differential topology
• Grantee: Daciberg Lima Gonçalves
• Support Opportunities: Research Projects - Thematic Grants