{ "id": "1011.0262", "version": "v1", "published": "2010-11-01T07:23:46.000Z", "updated": "2010-11-01T07:23:46.000Z", "title": "A characterization of compact operators via the non-connectedness of the attractors of a family of IFSs", "authors": [ "Alexandru Mihail", "Radu Miculescu" ], "comment": "12 pages", "categories": [ "math.FA" ], "abstract": "In this paper we present a result which establishes a connection between the theory of compact operators and the theory of iterated function systems. For a Banach space X, S and T bounded linear operators from X to X such that \\parallel S \\parallel, \\parallel T \\parallel <1 and w \\in X, let us consider the IFS S_{w}=(X,f_1,f_2), where f_1,f_2:X \\rightarrow X are given by f_1(x)=S(x) and f_2(x)=T(x)+w, for all x \\in X. On one hand we prove that if the operator S is compact, then there exists a family (K_{n})_{n \\in N} of compact subsets of X such that A_{S_{w}} is not connected, for all w \\in H- \\cup K_{n}. One the other hand we prove that if H is an infinite dimensional Hilbert space, then a bounded linear operator S:H \\rightarrow H having the property that \\parallel S \\parallel <1 is compact provided that for every bounded linear operator T:H\\rightarrow H such that \\parallel T \\parallel <1 there exists a sequence (K_{T,n})_{n} of compact subsets of H such that A_{S_{w}} is not connected for all w \\in H- \\cup K_{T,n}. Consequently, given an infinite dimensional Hilbert space H, there exists a complete characterization of the compactness of an operator S:H \\rightarrow H by means of the non-connectedness of the attractors of a family of IFSs related to the given operator.", "revisions": [ { "version": "v1", "updated": "2010-11-01T07:23:46.000Z" } ], "analyses": { "subjects": [ "28A80", "47B07", "54D05" ], "keywords": [ "compact operators", "bounded linear operator", "infinite dimensional hilbert space", "non-connectedness", "attractors" ], "note": { "typesetting": "TeX", "pages": 12, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2010arXiv1011.0262M" } } }