The ideal $(a)$ is not $G_\delta$ generated
Tom 125 / 2011
Colloquium Mathematicum 125 (2011), 7-14
MSC: Primary 03E15; Secondary 03E20, 28E15.
DOI: 10.4064/cm125-1-2
Streszczenie
We prove that the ideal $(a)$ defined by the density topology is not $G_\delta$ generated. This answers a question of Z. Grande and E. Strońska.