Set Notation

set

collection of elements

subset

part of a set

element

member of a set

empty set

set with no elements

null set

empty set

finite set

a set with a countable number of elements

infinite set

never-ending set e.g prime numbers

union

combined elements of two or more sets

intersection

common elements of two or more sets

{x|x>0}

The set of all x such that all x is greater than 0. Describes the properties that an element must have to be included in a set.

∈

Means an "element" of

⊂

Means a "proper subset" of

∪

Means a "Union" of

x∈A

"X" is an element of "A".

A⊂B

"A" is a proper subset of "B" or contained within "B".

A ⊆ B

A is a subset of B (and can also mean that A = B)

A∪B

"A" is a union of "B"

A∩B

"A" intersects "B"

A'

"A" compliment (what is not in A)

∉

Not an element of

⊄

Not a subset of

n(A)

The number of elements in A

∅ or { }

Empty set