Density point

of a set in an -dimensional space

A point at which the density of (cf. Density of a set) is equal to one. If the outer density is equal to one, the point is called an outer density point. A density point of a set is simultaneously a point of thinness for the complement of this set. Almost-all points in a measurable set are density points of it. By means of the concept of a density point one may introduce the concepts of approximate continuity and of an approximate derivative of a function.

Comments

For references see Density of a set.