Abstract.It is proved that the following spaces are absolute retracts: every F-space with a Schauder basis and certain function spaces along with their subgroups of integer-valued elements. It is also observed that for every o-compact convex set, the absolute extension property for compacta implies the AR-property.1. Introduction. The purpose of this paper is to provide new examples of infinite-dimensional ANRs. Detecting the ANR-property of convex subsets of nonlocally convex metric linear spaces and topological groups is of great importance. For example, the topological classification of these spaces, given recently in [4, 5 and 3], required the ANR-property. We prove that the following spaces are absolute retracts: (1) every complete metric linear space (= F-space) with a Schauder basis, (2) certain function spaces which include Lp (p 5= 0) and Orlicz spaces, and (3) additive subgroups consisting of all integer-valued functions in certain function spaces. Consequently, each of these spaces, when complete and separable, is homeomorphic to a Hubert space [4, 5]. The argument used in verifying the AR-property of the above examples is also employed to show that the AR and the AE(fé') (absolute extension property for compacta) properties coincide for a-compact convex sets. This enables us to find a dense convex topological copy of 2, the linear span of the Hilbert cube in the Hilbert space l2, in every separable infinite-dimensional complete convex set.Our approach is very elementary and mostly involves the natural equiconnected structures of convex sets and contractible groups. We also employ the admissibility
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.