• Media type: E-Article
  • Title: A Dual Characterization of Subdirectly Irreducible BAOs
  • Contributor: Venema, Yde
  • imprint: Kluwer Academic Publishers, 2004
  • Published in: Studia Logica: An International Journal for Symbolic Logic
  • Language: English
  • ISSN: 0039-3215; 1572-8730
  • Origination:
  • Footnote:
  • Description: <p>We give a characterization of the simple, and of the subdirectly irreducible boolean algebras with operators (including modal algebras), in terms of the dual descriptive frame, or, topological relational structure. These characterizations involve a special binary topo-reachability relation on the dual structure; we call a point u a topo-root of the dual structure if every ultrafilter is topo-reachable from u. We prove that a boolean algebra with operators is simple iff every point in the dual structure is a topo-root; and that it is subdirectly irreducible iff the collection of topo-roots is open and non-empty in the Stone topology on the dual structure iff this collection has non-empty interior in that topology.</p>