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The Boolean prime ideal theorem and products of cofinite topologies
Authors:Kyriakos Keremedis
Institution:University of the Aegean, Department of Mathematics, , Karlovasi Samos, 83200 Greece
Abstract:We show:
  1. The Boolean Prime Ideal theorem urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0001 is equivalent to each one of the statements:
    1. For every family urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0002 of compact spaces, for every family urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0003 of basic closed sets of the product urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0004 with the fip there is a family of subbasic closed sets urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0005 (urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0006) with the fip such that for every urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0007”.
    2. For every compact Loeb space urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0008 (the family of all non empty closed subsets of urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0009 has a choice function) and for every set X the product urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0010 is compact”.
  2. urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0011 (: the axiom of choice restricted to families of finite sets) implies “every well ordered product of cofinite topologies is compact” and “every well ordered basic open cover of a product of cofinite topologies has a finite subcover”.
  3. urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0012 (: the axiom of choice restricted to countable families of finite sets) iff “every countable product of cofinite topologies is compact”.
  4. urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0013 (: every filter of urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0014 extends to an ultrafilter) is equivalent to the proposition “for every compact Loeb space urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0015 having a base of size urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0016 and for every set X of size urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0017 the product urn:x-wiley:09425616:malq201100077:equation:malq201100077-math-0018 is compact”.
Keywords:Axiom of Choice  weak axioms of choice  Loeb spaces  Tychonoff products  Boolean prime ideal theorem  E325  54A35  54B10
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