**Set Theory Symbols**

∈ “is an element of”

∉ “is not an element of”

⊂ “is a *proper *subset of”

⊆ “is a subset of”

⊄ “is not a subset of”

∅ the empty set; a set with no elements

∩ intersection

∪ union

or *A*’ “the compliment of A”; all elements not in A

*A – B *all elements in *A *but not in *B*

*n*(*A*) “the number of elements in *A*”

*A = B *“*A *is equal to *B*”; *A *and *B *contain the same elements

*A *≅ *B *“*A *is equivalent to *B*”; *A *and *B *contain the same

number of elements