1 in notes

sezrurkle lujvo

x₁ is an open set in the topological space x₂.

x₂ is conceptually composed of an underlying set, which is a superset of x₁, and topological information/defining information; however, it can also be expressed as a set of some of the subsets of the said underlying (implicitly define) set. Confer: "sezbarkle".

• jbovlaste

In notes:

sezbarkle

x₁ (metric space/set/class/structure) is a metric subspace/subset(/subclass) of x₂ (metric space/set/class) which is closed therein. x₁ is an closed subset of x₂, where closedness is taken to be understood as being considered within x₂ and under the metric shared by x₁ and x₂