Ultrafilters and Decompositions of Abelian Groups

• Дата: 2001
• Автори: Protasov, I. V., Протасов, И. В.
• Формат: Стаття
• Мова: Російська; Англійська
• Опубліковано: Institute of Mathematics, NAS of Ukraine 2001
• Онлайн доступ: https://umj.imath.kiev.ua/index.php/umj/article/view/4224
• Назва журналу: Ukrains’kyi Matematychnyi Zhurnal

We prove that every PS-ultrafilter on a group without second-order elements is a Ramsey ultrafilter. For an arbitrary PS-ultrafilter ϕ on a countable group G, we construct a mapping f: G → ω such that f(ϕ) is a P-point in the space ω*. We determine a new class of subselective ultrafilters, which is...