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Retraction spaces and the homotopy metric
Authors:Laurence Boxer
Institution:Department of Mathematics, Muhlenberg College, Allentown, PA 18104, USA
Abstract:Let X be a finite-dimensional compactum. Let R(X) and N(X) be the spaces of retractions and non-deformation retractions of X, respectively, with the compact-open (=sup-metric) topology. Let 2Xh be the space of non-empty compact ANR subsets of X with topology induced by the homotopy metric. Let RXh be the subspace of 2Xh consisting of the ANR's in X that are retracts of X.We show that N(Sm) is simply-connected for m > 1. We show that if X is an ANR and A0?RXh, then limi→∞Ai=A0 in 2Xh if and only if for every retraction r0 of X onto A0 there are, for almost all i, retractions ri of X onto Ai such that limi→∞ri=ro in R(X). We show that if X is an ANR, then the local connectedness of R(X) implies that of RXh. We prove that R(M) is locally connected if M is a closed surface. We give examples to show how some of our results weaken when X is not assumed to be an ANR.
Keywords:54B20  54C35  54C15  54F40  55D99  57A05  57A10  57A15  Retraction  deformation retraction  sup-metric  finite dimensional compactum  ANR  homotopy metric  Hausdorff metric  homotopy domination  FANR  fundamental retraction  movable
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