51. CMB 1997 (vol 40 pp. 448)
 Kaczynski, Tomasz; Mrozek, Marian

Stable index pairs for discrete dynamical systems
A new shorter proof of the existence of index pairs for discrete
dynamical systems is given. Moreover, the index pairs defined in
that proof are stable with respect to small perturbations of the
generating map. The existence of stable index pairs was previously
known in the case of diffeomorphisms and flows generated by smooth
vector fields but it was an open question in the general discrete
case.
Categories:54H20, 54C60, 34C35 

52. CMB 1997 (vol 40 pp. 422)
 Dow, Alan

On compact separable radial spaces
If ${\cal A} $ and ${\cal B}$ are disjoint ideals on $\omega$, there is
a {\it tower preserving\/} $\sigma$centered forcing which introduces a
subset of $\omega$ which meets every infinite member of ${\cal A}$ in
an infinite set and is almost disjoint from every member of ${\cal B}$.
We can then produce a model in which all compact separable radial
spaces are Fr\'echet, thus answering a question of P.~Nyikos. The
question of the existence of compact ccc radial spaces which are not
Fr\'echet was first asked by Chertanov (see \cite{Ar78}).
Category:54D30 

53. CMB 1997 (vol 40 pp. 39)
 Zhao, Dongsheng

On projective $Z$frames
This paper deals with the projective objects in the category of all
$Z$frames, where the latter is a common generalization of
different types of frames. The main result obtained here is that a
$Z$frame is ${\bf E}$projective if and only if it is stably
$Z$continuous, for a naturally arising collection ${\bf E}$ of morphisms.
Categories:06D05, 54D10, 18D15 
