EntityQ842620· pop 21· linked from 282 articlesdisjoint unionSign in to savemodified union operation that indexes the elements according to which set they originated inConnectionsordered pairEntitypartition of a setEntitysymmetric differenceEntitytagged unionEntitymathematicsEntityBertrand RussellEntityInternational Standard Book NumberEntityset theoryEntityJohn von NeumannEntitysetEntityaxiomEntityGeorg CantorEntityKurt GödelEntityRichard DedekindEntityempty setEntitysubsetEntityCartesian productEntityunionEntityWillard Van Orman QuineEntityintersectionEntityCategoriesBasic concepts in set theoryOperations on sets