2023/05/28 by Gutman, Yonatan, Levin, Michael, Meyerovitch, Tom
#37B99 #57M60 #Dynamical Systems (math.DS) #FOS: Mathematics #General Topology (math.GN)
paper · doi:10.48550/arxiv.2305.17717
We prove an equivariant version of the classical Menger-Nobeling theorem regarding topological embeddings: Whenever a group G acts on a finite-dimensional compact metric space X, a generic continuous equivariant function from X into ([0,1]r)G is a topological embedding, provided that for every positive integer N the space of points in X with orbit size at most N has topological dimension strictly less than (rN)/(2). We emphasize that the result imposes no restrictions whatsoever on the acting group G (beyond the existence of an action on a finite-dimensional space). Moreover, if G is finitely generated then there exists a finite subset F⊂ G so that for a generic continuous map h:X→ [0,1]r, the map hF:X→ ([0,1]r)F given by x↦ (f(gx))g∈ F is an embedding. This constitutes a generalization of the Takens delay embedding theorem into the topological category.