English

Diagonals separating the square of a continuum

General Topology 2022-12-21 v1 Dynamical Systems

Abstract

A metric continuum XX is indecomposable if it cannot be put as the union of two of its proper subcontinua. A subset RR of XX is said to be continuumwise connected provided that for each pair of points p,qRp,q\in R, there exists a subcontinuum MM of XX such that {p,q}MR\{p,q\}\subset M\subset R. Let X2X^{2} denote the Cartesian square of XX and Δ\Delta the diagonal of X2X^{2}. In \cite{ka} it was asked if for a continuum XX, distinct from the arc, X2ΔX^{2}\setminus \Delta is continuumwise connected if and only if XX is decomposable. In this paper we show that no implication in this question holds. For the proof of the non-necessity, we use the dynamic properties of a suitable homeomorphism of the Cantor set onto itself to construct an appropriate indecomposable continuum XX.

Keywords

Cite

@article{arxiv.2212.09893,
  title  = {Diagonals separating the square of a continuum},
  author = {Alejandro Illanes and Verónica Martínez-de-la-Vega and Jorge M. Martínez-Montejano and Daria Michalik},
  journal= {arXiv preprint arXiv:2212.09893},
  year   = {2022}
}