Andrea Medini

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2ranked-venue papers
2as first author
1since 2021 · last 2024
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Theory of computation · 2 · 2 first-author · 1 since 2021
YearPublicationVenuePosition
2024 Zero-dimensional σ-homogeneous spaces
Andrea Medini, Zoltán Vidnyánszky
Ann. Pure Appl. Log.1
2016 Distinguishing Perfect Set Properties in separable metrizable Spaces
abstract
Abstract All spaces are assumed to be separable and metrizable. Our main result is that the statement “For every space X, every closed subset of X has the perfect set property if and only if every analytic subset of X has the perfect set property” is equivalent to b > ω1 (hence, in particular, it is independent of ZFC). This, together with a theorem of Solecki and an example of Miller, will allow us to determine the status of the statement “For every space X, if every Γ subset of X has the perfect set property then every Γ′ subset of X has the perfect set property” as Γ, Γ′ range over all pointclasses of complexity at most analytic or coanalytic. Along the way, we define and investigate a property of independent interest. We will say that a subset W of 2ω has the Grinzing property if it is uncountable and for every uncountable Y ⊆ W there exists an uncountable collection consisting of uncountable subsets of Y with pairwise disjoint closures in 2ω. The following theorems hold. (1) There exists a subset of 2ω with the Grinzing property. (2) Assume MA + ¬CH. Then 2ω has the Grinzing property. (3) Assume CH. Then 2ω does not have the Grinzing property. The first result was obtained by Miller using a theorem of Todorčević, and is needed in the proof of our main result.
Andrea Medini
J. Symb. Log.1