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More on cardinal invariants of analytic P -ideals

Barnabás FarkasLajos Soukup — 2009

Commentationes Mathematicae Universitatis Carolinae

Given an ideal on ω let 𝔞 ( ) ( 𝔞 ¯ ( ) ) be minimum of the cardinalities of infinite (uncountable) maximal -almost disjoint subsets of [ ω ] ω . We show that 𝔞 ( h ) > ω if h is a summable ideal; but 𝔞 ( 𝒵 μ ) = ω for any tall density ideal 𝒵 μ including the density zero ideal 𝒵 . On the other hand, you have 𝔟 𝔞 ¯ ( ) for any analytic P -ideal , and 𝔞 ¯ ( 𝒵 μ ) 𝔞 for each density ideal 𝒵 μ . For each ideal on ω denote 𝔟 and 𝔡 the unbounding and dominating numbers of ω ω , where f g iff { n ω : f ( n ) > g ( n ) } . We show that 𝔟 = 𝔟 and 𝔡 = 𝔡 for each analytic P -ideal . Given a Borel ideal on...

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