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