Separability is one of the most basic and important topological properties.
In this paper, the separability in (strongly) topological gyrogroups is
studied. It is proved that every first-countable left ?-narrow strongly
topological gyrogroup is separable. Furthermore, it is shown that if a
feathered strongly topological gyrogroup G is isomorphic to a subgyrogroup
of a separable strongly topological gyrogroup, then G is separable.
Therefore, if a metrizable strongly topological gyrogroup G is isomorphic to
a subgyrogroup of a separable strongly topological gyrogroup, then G is
separable, and if a locally compact strongly topological gyrogroup G is
isomorphic to a subgyrogroup of a separable strongly topological gyrogroup,
then G is separable.