A topological property enjoyed by near points but not by large points |
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Authors: | Jan van Mill Charles F. Mills |
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Affiliation: | Subfaculteit Wiskunde, Vrije Universiteit, De Boelelaan 1081, Amsterdam, The Netherlands |
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Abstract: | Let H denote the halfline [0,∞). A point p?βH?H is called a near point if p is in the closure of some countable discrete closed subspace of H. In addition, a point p?βH?H is called a large point if p is not in the closure of a closed subset of H of finite Lebesgue measure. We will show that for every autohomeomorphism ? of βH?H and for each near point p we have that ?(p) is not large. In addition, we establish, under CH, the existence of a point x?βH?H such that for each autohomeomorphism ? of βH?H the point ?(x) is neither large nor near. |
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Keywords: | 54D35 |
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