Displaying similar documents to “On some problem of A. Rosłanowski”

Very small sets

Haim Judah, Amiran Lior, Ireneusz Recław (1997)

Colloquium Mathematicae

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On c-sets and products of ideals

Marek Balcerzak (1991)

Colloquium Mathematicae

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Let X, Y be uncountable Polish spaces and let μ be a complete σ-finite Borel measure on X. Denote by K and L the families of all meager subsets of X and of all subsets of Y with μ measure zero, respectively. It is shown that the product of the ideals K and L restricted to C-sets of Selivanovskiĭ is σ-saturated, which extends Gavalec's results.

Comparison game on Borel ideals

Michael Hrušák, David Meza-Alcántara (2011)

Commentationes Mathematicae Universitatis Carolinae

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We propose and study a “classification” of Borel ideals based on a natural infinite game involving a pair of ideals. The game induces a pre-order ⊑ and the corresponding equivalence relation. The pre-order is well founded and “almost linear”. We concentrate on F σ and F σ δ ideals. In particular, we show that all F σ -ideals are ⊑ -equivalent and form the least equivalence class. There is also a least class of non- F σ Borel ideals, and there are at least two distinct classes of F σ δ non- F σ ideals. ...