Tree-likeness of hereditarily equivalent continua
نویسندگان
چکیده
منابع مشابه
On Finitely Equivalent Continua
A continuum means a compact connected metric space. For a positive integer n, a continuum X is said to be n-equivalent provided that X contains exactlyn topologically distinct subcontinua. A continuumX is said to be hereditarily n-equivalent provided that each nondegenerate subcontinuum of X is n-equivalent. If there exists a positive integer n such that X is n-equivalent, then X is said to be ...
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For a hereditarily unicoherent continuum X, its kernel means the common part of all subcontinua of X that intersect all arc components of X. This concept naturally appears when absolute retracts for the class of hereditarily unicoherent continua are studied. Let Y be such an absolute retract. Among other results, we prove that (a) Y is indecomposable if and only if it is identical with its kern...
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Let X be a Hausdorff continuum (a compact connected Hausdorff space). Let 2X (respectively, Cn(X)) denote the hyperspace of nonempty closed subsets of X (respectively, nonempty closed subsets of X with at most n components), with the Vietoris topology. We prove that if X is hereditarily indecomposable, Y is a Hausdorff continuum and 2X (respectively Cn(X)) is homeomorphic to 2Y (respectively, C...
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Inverse limits with set-valued functions having graphs that are the union of mappings have attracted some attention over the past few years. In this paper we show that if the graph of a surjective set-valued function f : [0, 1] → 2[0,1] is the union of two mappings having only one point (x, x) in common such that x is not the image of any other point of the interval under f , then its inverse l...
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We study the classical NP-hard problems of finding maximum-size subsets from given sets of k terminal pairs that can be routed via edge-disjoint paths (MaxEDP) or node-disjoint paths (MaxNDP) in a given graph. The approximability of MaxEDP/NDP is currently not well understood; the best known lower bound is Ω(log1/2−ε n), assuming NP 6⊆ ZPTIME(n ). This constitutes a significant gap to the best ...
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ژورنال
عنوان ژورنال: Fundamenta Mathematicae
سال: 1970
ISSN: 0016-2736,1730-6329
DOI: 10.4064/fm-68-2-203-205