Andrzej Szymanski
On $\pi $--caliber and an application of Prikry's partial order

Comment.Math.Univ.Carolin. 52,3 (2011) 463-471.

Abstract:We study the concept of $\pi $-caliber as an alternative to the well known concept of caliber. $\pi $-caliber and caliber values coincide for regular cardinals greater than or equal to the Souslin number of a space. Unlike caliber, $\pi $-caliber may take on values below the Souslin number of a space. Under Martin's axiom, $2^{\omega }$ is a $\pi $-caliber of $\mathbb{N}^{\ast }$. Prikry's poset is used to settle a problem by Fedeli regarding possible values of very weak caliber.

Keywords: nowhere dense, point-$\kappa $ family, $\pi $-caliber
AMS Subject Classification: 54A38 54A15 03E35

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