For any topologies$\tau_1 \subseteq \tau_2$, we consider the idealof sets $A$ such that for each nonempty$U \in \tau_2$ there exists $W \in \tau_1$such that $U \cap W \not= \emptyset$ and$A \cap U \cap W = \emptyset$.For $\tau_1$, the standard Euclidean topology,and for $\tau_2$, the density topology, we obtain the ideal $\aideal$investigated by Z.Grande and E.Stro\'nska.
@article{75,
title = {Notes on the ideal $(a)$},
journal = {Tatra Mountains Mathematical Publications},
volume = {45},
year = {2010},
doi = {10.2478/tatra.v46i0.75},
language = {EN},
url = {http://dml.mathdoc.fr/item/75}
}
Nowik, Andrzej. Notes on the ideal $(a)$. Tatra Mountains Mathematical Publications, Tome 45 (2010) . doi : 10.2478/tatra.v46i0.75. http://gdmltest.u-ga.fr/item/75/