Union, Intersection and Difference
Sets combine through the union , the intersection , and the difference ; and are disjoint when .
Definition 2.4 (Set Operations)
If and are sets, then
- their union
- their intersection .
- and are disjoint if .
- their difference .
Indexed families
For sets the operations extend to and . More generally, for a collection indexed by a set , and . The symbol here records the index set ; it does not mean the limit of anything.
Related
Stated in
- Definition 2.4 (Set Operations)§2.1.1 Introduction on Sets