2017
Том 69
№ 9

All Issues

Ultrafilters and Decompositions of Abelian Groups

Protasov I. V.

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Abstract

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 considerably wider than the class of PS-ultrafilters.

English version (Springer): Ukrainian Mathematical Journal 53 (2001), no. 1, pp 99-107.

Citation Example: Protasov I. V. Ultrafilters and Decompositions of Abelian Groups // Ukr. Mat. Zh. - 2001. - 53, № 1. - pp. 85-93.

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