Definition:Empty


 * Set Theory and Class Theory:
 * Empty set
 * Empty class
 * Empty mapping
 * Empty relation


 * Graph Theory:
 * Empty graph, also known as an edgeless graph


 * Algebra and Abstract Algebra:
 * Empty sum


 * Descriptive Statistics:
 * Empty class, also known as an empty class interval


 * Category Theory:
 * Empty category

Also see

 * Definition:Vacuous
 * Definition:Zero
 * Definition:Trivial
 * Definition:Degenerate