
The weak ideal property and topological dimension zero
Following up on previous work,
we prove a number of results for C*algebras
with the weak ideal property
or topological dimension zero,
and some results for C*algebras with related properties.
Some of the more important results include:
$\bullet$
The weak ideal property
implies topological dimension zero.
$\bullet$
For a separable C*algebra~$A$,
topological dimension zero is equivalent to
${\operatorname{RR}} ({\mathcal{O}}_2 \otimes A) = 0$,
to $D \otimes A$ having the ideal property
for some (or any) Kirchberg algebra~$D$,
and to $A$ being residually hereditarily in
the class of all C*algebras $B$ such that
${\mathcal{O}}_{\infty} \otimes B$
contains a nonzero projection.
$\bullet$
Extending the known result for ${\mathbb{Z}}_2$,
the classes of C*algebras
with residual (SP),
which are residually hereditarily (properly) infinite,
or which are purely infinite and have the ideal property,
are closed under crossed products by arbitrary actions
of abelian $2$groups.
$\bullet$
If $A$ and $B$ are separable,
one of them is exact,
$A$ has the ideal property,
and $B$ has the weak ideal property,
then $A \otimes_{\mathrm{min}} B$ has the weak ideal property.
$\bullet$
If $X$ is a totally disconnected locally compact Hausdorff space
and $A$ is a $C_0 (X)$algebra
all of whose fibers have one of the weak ideal property,
topological dimension zero,
residual (SP),
or the combination of pure infiniteness and the ideal property,
then $A$ also has the corresponding property
(for topological dimension zero, provided $A$ is separable).
$\bullet$
Topological dimension zero,
the weak ideal property,
and the ideal property
are all equivalent
for a substantial class of separable C*algebras including
all separable locally AH~algebras.
$\bullet$
The weak ideal property does not imply the ideal property
for separable $Z$stable C*algebras.
We give other related results,
as well as counterexamples to several other statements
one might hope for.
Keywords:ideal property, weak ideal property, topological dimension zero, $C_0 (X)$algebra, purely infinite C*algebra Category:46L05 