12,925 research outputs found

    Even more simple cardinal invariants

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    Using GCH, we force the following: There are continuum many simple cardinal characteristics with pairwise different values.Comment: a few changes (minor corrections) from first versio

    The Higher Cicho\'n Diagram

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    For a strongly inacessible cardinal κ\kappa, we investigate the relationships between the following ideals: - the ideal of meager sets in the <κ{<}\kappa-box product topology - the ideal of "null" sets in the sense of [Sh:1004] (arXiv:1202.5799) - the ideal of nowhere stationary subsets of a (naturally defined) stationary set Sprκ⊆κS_{\rm pr}^\kappa \subseteq \kappa. In particular, we analyse the provable inequalities between the cardinal characteristics for these ideals, and we give consistency results showing that certain inequalities are unprovable. While some results from the classical case (κ=ω\kappa=\omega) can be easily generalized to our setting, some key results (such as a Fubini property for the ideal of null sets) do not hold; this leads to the surprising inequality cov(null)≤\lenon(null). Also, concepts that did not exist in the classical case (in particular, the notion of stationary sets) will turn out to be relevant. We construct several models to distinguish the various cardinal characteristics; the main tools are iterations with <κ\mathord<\kappa-support (and a strong "Knaster" version of κ+\kappa^+-cc) and one iteration with ≤κ{\le}\kappa-support (and a version of κ\kappa-properness).Comment: 84 page

    Many Different Uniformity Numbers of Yorioka Ideals

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    Using a countable support product of creature forcing posets, we show that consistently, for uncountably many different functions the associated Yorioka ideals' uniformity numbers can be pairwise different. In addition we show that, in the same forcing extension, for two other types of simple cardinal characteristics parametrised by reals (localisation and anti-localisation cardinals), for uncountably many parameters the corresponding cardinals are pairwise different.Comment: 29 pages, 4 figure

    Preserving levels of projective determinacy by tree forcings

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    We prove that various classical tree forcings -- for instance Sacks forcing, Mathias forcing, Laver forcing, Miller forcing and Silver forcing -- preserve the statement that every real has a sharp and hence analytic determinacy. We then lift this result via methods of inner model theory to obtain level-by-level preservation of projective determinacy (PD). Assuming PD, we further prove that projective generic absoluteness holds and no new equivalence classes classes are added to thin projective transitive relations by these forcings.Comment: 3 figure
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