Open set
SET THAT DOES NOT CONTAIN ANY OF ITS BOUNDARY POINTS
Open subset; Open (topology); Open region; Open subsets; Open sets; Open (mathematics); Open superset; ⟃; ⟄
In mathematics, open sets are a generalization of open intervals in the real line. In a metric space—that is, when a distance function is defined—open sets are the sets that, with every point , contain all points that are sufficiently near to (that is, all points whose distance to is less than some value depending on ).