Ultrafilter spaces and compactifications.
Given a free ultrafilter on and a space , we say that is the -limit point of a sequence in (in symbols, -) if for every neighborhood of , . By using -limit points from a suitable metric space, we characterize the selective ultrafilters on and the -points of . In this paper, we only consider dynamical systems , where is a compact metric space. For a free ultrafilter on , the function is defined by - for each . These functions are not continuous in general. For a...