On the complexity of the ideal of absolute null sets

• Date: 2012
• Main Authors: Zakrzewski, P., Закржевскі, П.
• Format: Article
• Language: English
• Published: Institute of Mathematics, NAS of Ukraine 2012
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/2574
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

Answering a question of Banakh and Lyaskovska, we prove that for an arbitrary countable infinite amenable group $G$ the ideal of sets having $\mu$-measure zero for every Banach measure $\mu$ on $G$ is an $F_{\sigma \delta}$ subset of $\{0,1\}^G$.