In Topology , a Regular Space is one in which points are closed and any point can be separated from any closed set by open sets.
In Algebraic Geometry , a function is regular on a Variety if for every point there exists an open neighborhood so that the function restricts to a rational function whose denominator does not vanish in that neighborhood.
In Information Theory , data with regularity has less Entropy than its representation suggests. For example, EnglishProse is quite regular because most random sequences of Alphabetic and Punctuative characters are not valid English prose.
In Analysis , regularity refers to the degree of differentiability or Smoothness of a function.