Definition:Empty


 * Set Theory and Class Theory::
 * Definition:Empty Set
 * Definition:Empty Class (Class Theory)
 * Definition:Empty Mapping
 * Definition:Empty Relation


 * Category Theory:
 * Definition:Empty Category


 * Algebra and Abstract Algebra:
 * Definition:Empty Sum

Also see

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