Reconstructing compact metrizable spaces
The deck, D(X), of a topological space X is the set D(X) = {[X\{x}]: x ∈ X}, where [Y] denotes the homeomorphism class of Y. A space X is (topologically) reconstructible if whenever D(Z) = D(X), then Z is homeomorphic to X. It is known that every (metrizable) continuum is reconstructible, whereas th...
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| Médium: | Journal article |
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American Mathematical Society
2016
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| Shrnutí: | The deck, D(X), of a topological space X is the set D(X) = {[X\{x}]: x ∈ X}, where [Y] denotes the homeomorphism class of Y. A space X is (topologically) reconstructible if whenever D(Z) = D(X), then Z is homeomorphic to X. It is known that every (metrizable) continuum is reconstructible, whereas the Cantor set is non-reconstructible. The main result of this paper characterises the non-reconstructible compact metrizable spaces as precisely those where for each point x there is a sequence <bx n="" n:="" ℕ="" ∈=""> of pairwise disjoint clopen subsets converging to x such that Bxn and Byn are homeomorphic for each n and all x and y. In a non-reconstructible compact metrizable space the set of 1-point components forms a dense Gδ. For h-homogeneous spaces, this condition is sufficient for non-reconstruction. A wide variety of spaces with a dense Gδ set of 1-point components is presented, some reconstructible and others not reconstructible.</bx> |
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