2017/03/10 by Ігор Протасов, Protasov, Igor, Ksenia Protasova +1
Mathematics · #Advanced Topology and Set Theory #FOS: Mathematics #General Topology (math.GN) #Limits and Structures in Graph Theory #Mathematical and Theoretical Analysis
paper · pdf · doi:10.48550/arxiv.1703.03834
openalex publication_date 2017/03/10 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/28
We say that a subset S of an infinite group G is a Ramsey-product subset if, for any infinite subsets X, Y of G, there exist x ∈ X and y∈ Y such that x y ∈ S and y x ∈ S . We show that the family φ of all Ramsey-product subsets of G is a filter and φ defines the subsemigroup G^*G^* of the semigroup G^* of all free ultrafilters on G.