Let be the Cantor set, let be the point , and let , for , denote the line segment connecting to . If is an endpoint of an interval deleted in the Cantor set, let ; for all other points in let ; the Knaster–Kuratowski fan is defined as equipped with the subspace topology inherited from the standard topology on .
The fan itself is connected, but becomes totally disconnected upon the removal of .
knaster, kuratowski, topology, branch, mathematics, named, after, polish, mathematicians, bronisław, knaster, kazimierz, kuratowski, specific, connected, topological, space, with, property, that, removal, single, point, makes, totally, disconnected, also, know. In topology a branch of mathematics the Knaster Kuratowski fan named after Polish mathematicians Bronislaw Knaster and Kazimierz Kuratowski is a specific connected topological space with the property that the removal of a single point makes it totally disconnected It is also known as Cantor s leaky tent or Cantor s teepee after Georg Cantor depending on the presence or absence of the apex The Knaster Kuratowski fan or Cantor s teepee Let C displaystyle C be the Cantor set let p displaystyle p be the point 1 2 1 2 R 2 displaystyle left tfrac 1 2 tfrac 1 2 right in mathbb R 2 and let L c displaystyle L c for c C displaystyle c in C denote the line segment connecting c 0 displaystyle c 0 to p displaystyle p If c C displaystyle c in C is an endpoint of an interval deleted in the Cantor set let X c x y L c y Q displaystyle X c x y in L c y in mathbb Q for all other points in C displaystyle C let X c x y L c y Q displaystyle X c x y in L c y notin mathbb Q the Knaster Kuratowski fan is defined as c C X c displaystyle bigcup c in C X c equipped with the subspace topology inherited from the standard topology on R 2 displaystyle mathbb R 2 The fan itself is connected but becomes totally disconnected upon the removal of p displaystyle p See also EditAntoine s necklaceReferences EditKnaster B Kuratowski C 1921 Sur les ensembles connexes PDF Fundamenta Mathematicae 2 1 206 255 doi 10 4064 fm 2 1 206 255 Steen Lynn Arthur Seebach J Arthur Jr 1995 1978 Counterexamples in Topology Dover reprint of 1978 ed Berlin New York Springer Verlag ISBN 978 0 486 68735 3 MR 0507446 This topology related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Knaster Kuratowski fan amp oldid 1065706756, wikipedia, wiki, book, books, library,