Space S000057
Rational sequence topology
For each irrational fix a sequence of rational numbers . The rational sequence topology on is defined by declaring each rational point open and letting be a local basis at each irrational .
Note that in MathOverflow 447593 it was shown there are distinct topologies defined in this way, depending on the choices made for . However, none of the properties currently tracked for this space rely on this information.
Defined as counterexample #65 ("Rational Sequence Topology") in DOI 10.1007/978-1-4612-6290-9.