The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

The search session has expired. Please query the service again.

Displaying similar documents to “A note on the intersection ideal 𝒩

Pcf theory and cardinal invariants of the reals

Lajos Soukup (2011)

Commentationes Mathematicae Universitatis Carolinae

Similarity:

The additivity spectrum ADD ( ) of an ideal 𝒫 ( I ) is the set of all regular cardinals κ such that there is an increasing chain { A α : α < κ } with α < κ A α . We investigate which set A of regular cardinals can be the additivity spectrum of certain ideals. Assume that = or = 𝒩 , where denotes the σ -ideal generated by the compact subsets of the Baire space ω ω , and 𝒩 is the ideal of the null sets. We show that if A is a non-empty progressive set of uncountable regular cardinals and pcf ( A ) = A , then ADD ( ) = A in some c.c.c generic extension...

More on cardinal invariants of analytic P -ideals

Barnabás Farkas, Lajos Soukup (2009)

Commentationes Mathematicae Universitatis Carolinae

Similarity:

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...

On nonmeasurable images

Robert Rałowski, Szymon Żeberski (2010)

Czechoslovak Mathematical Journal

Similarity:

Let ( X , 𝕀 ) be a Polish ideal space and let T be any set. We show that under some conditions on a relation R T 2 × X it is possible to find a set A T such that R ( A 2 ) is completely 𝕀 -nonmeasurable, i.e, it is 𝕀 -nonmeasurable in every positive Borel set. We also obtain such a set A T simultaneously for continuum many relations ( R α ) α < 2 ω . Our results generalize those from the papers of K. Ciesielski, H. Fejzić, C. Freiling and M. Kysiak.