A separable metric space is completely metrizable if and only if the second player has a winning strategy in this game.
For separable spaces, the notions of weak and strong measurability agree.
Let X be an arbitrary separable metric space.
The two notions above agree for separable, metrisable spaces.
Now let be a complete separable metric space, the phase space.
Any continuous image of a separable space is separable .
A product of at most continuum many separable spaces is separable.
The notions of regularity and completeness are incompatible in a separable space.
With respect to either σ or σ, D is a separable space.
R is not metrizable, since separable metric spaces are second-countable.