Additivity of porous sets (Q2276787)

The main result of the paper is the following theorem: If I is a sigma- ideal of subsets of real numbers included between the sigma-ideal of sigma-porous sets and the sigma-ideal of sets of the first category, then the additivity of I is not greater than the cardinality of an arbitrary unbounded subset of \(^{\omega}\omega\) and the cofinality of I is not less than the cardinality of an arbitrary dominating subset of \(^{\omega}\omega\).