Displaying similar documents to “Topological games and products, III”

A game and its relation to netweight and D-spaces

Gary Gruenhage, Paul Szeptycki (2011)

Commentationes Mathematicae Universitatis Carolinae

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We introduce a two player topological game and study the relationship of the existence of winning strategies to base properties and covering properties of the underlying space. The existence of a winning strategy for one of the players is conjectured to be equivalent to the space have countable network weight. In addition, connections to the class of D-spaces and the class of hereditarily Lindelöf spaces are shown.

A dichotomy on Schreier sets

Robert Judd (1999)

Studia Mathematica

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We show that the Schreier sets S α ( α < ω 1 ) have the following dichotomy property. For every hereditary collection ℱ of finite subsets of ℱ, either there exists infinite M = ( m i ) i = 1 ∞ ⊆ ℕ such that S α ( M ) = m i : i ∈ E : E ∈ S α ⊆ ℱ , or there exist infinite M = ( m i ) i = 1 ∞ , N ⊆ ℕ such that ℱ [ N ] ( M ) = m i : i ∈ F : F ∈ ℱ a n d F ⊂ N ⊆ S α .