Topology and its Applications ( IF 0.6 ) Pub Date : 2021-02-23 , DOI: 10.1016/j.topol.2021.107636 Mauricio E. Chacón-Tirado , Alejandro Illanes
For a metric continuum X, we consider the hyperspace of subcontinua of X, with the Hausdorff metric. A Whitney mapping is a continuous function such that: (a) for each , , and (b) if and , then . The Whitney mapping μ is finitely generated if there exist a finite number of continuous functions such that for each , . In this paper we study the continua X for which there exist finitely generated Whitney mappings. In particular, when X is a tree, we find relations among the number of necessary mappings to generate a Whitney mapping with: the number of necessary arcs for covering X; the number of end-points of X; the disconnection number of X; the dimension of and the number n for which X is an n-od.
中文翻译:
有限生成的惠特尼映射
对于度量连续体X,我们考虑子连续体的超空间的X,与豪斯多夫度量。惠特尼映射是一个连续函数 这样:(a)每个 , ,以及(b)如果 和 , 然后 。如果存在有限数量的连续函数,则将有限生成惠特尼映射μ 这样每个 , 。在本文中,我们研究了康体X为其中存在有限生成惠特尼映射。特别是,当X是一棵树,我们发现需要映射产生了惠特尼映射的数量之间的关系:覆盖必要的弧的数目X ; X的端点数;X的断开数; 的尺寸和数量Ñ为其X为Ñ -od。