Stone spaces of some Boolean algebras
R. A. Golovastov Udmurt State University, ul. Universitetskaya, 1, Izhevsk, 426034, Russia
Abstract:
We study the Stone spaces of some Boolean algebras and establish relations between subsets of this spaces and Chech–Stone space
$\beta\omega$, Cantor set, and other spaces. We consider three countable partially ordered sets and two type of Boolean algebras for each set. First, we consider space
$S\mathfrak B_{1,1}$ constructered by M. Bell. We prove existence of subsets homeomorphic to
$\beta\omega$ and convergent sequences in
$S\mathfrak B_{1,1}$. For space
$S\mathfrak B_{1,2}$, we prove that there are clopen subsets which is homeomorphic to
$\beta\omega$ and remainder
$S\mathfrak B_{1,2}^*$ consists of isolated points. We describe clopen subsets of
$S\mathfrak B_{1,1}$ which are gomeomorphic to
$\beta\omega$. We construct two examples: subset of
$\mathfrak{N}_2$ which closure is non-open copy of
$\beta\omega$ and subset of
$\mathfrak{N}_2$ which closure is clopen and not gomeomorphic to
$\beta\omega$.
$S\mathfrak B_{1,2}$ is closure subset of
$S\mathfrak B_{1,1}$ and
$S\mathfrak B_{1,2}^*$ is nowhere dense in
$S\mathfrak B_{1,1}^*$. Next, we consider the space
$S\mathfrak B_{1,3}$. The subspace of free ultrafilters of
$S\mathfrak B_{1,3}$ has the countable Suslin number, but is not separable. The points of the space are described as ultrafilters possessing basis of certain types. Next, we consider the spaces
$S\mathfrak B_{2,1}$,
$S\mathfrak B_{2,2}$, and
$S\mathfrak B_{2,3}$. Boolean algebras for those Stone spaces have more simple structure.
$S\mathfrak B_{2,3}$ is homeomorphic to Cantor set. The subset of free ultrafilters
$S\mathfrak B_{2,3}^*$ is homeomorphic to the set of irrational numbers with natural topology. The subsets of free ultrafilters
$S\mathfrak B_{1,3}^*$ and
$S\mathfrak B_{1,3}^*$ are homeomorphic to Cantor set.
Keywords:
compactification, Boolean algebra, Stone space, ultrafilter.
UDC:
515.122.536
MSC: 54D35 Received: 30.03.2015