Том 70
№ 9

All Issues

Ultrafilters on balleans

Protasov I. V., Slobodianiuk S. V.


A ballean (equivalently, a coarse structure) is an asymptotic counterpart of a uniform space. We introduce three ultrafilter satellites of a ballean (namely, corona, companion, and corona companion), evaluate the basic cardinal invariants of the corona and characterize the subsets of balleans in terms of companions.

Citation Example: Protasov I. V., Slobodianiuk S. V. Ultrafilters on balleans // Ukr. Mat. Zh. - 2015. - 67, № 12. - pp. 1698-1706.