Set Notation

∈

is an element of

∉

is not an element of

⊆

is a subset of

⊂

is a proper subset of

{x₁,x₂, …}

the set with elements x₁,x₂ etc.

{ x : …}

the set of all x such that..

n(A)

the number of elements in set A

∅

the empty set

ε

the universal set

A′

the complement of the set A

ℕ

the set of natural numbers {1, 2, 3, …}

ℤ

the set of integer numbers {0, ±1, ±2, ±3, …}

ℤ+

the set of positive integers {1, 2, 3, …}

ℤ₀⁺

the set of non-negative integers {0, 1, 2, 3, …}

ℝ

the set of real numbers

ℚ

the set of rational numbers {p/q : p ∈ ℤ, q ∈ ℤ₀⁺ }

∪

union

∩

intersection

(x, y)

the ordered pair x,y

[a, b]

the closed interval {x ∈ ℝ: a ≤ x ≤ b}

[a,b)

the interval {x ∈ ℝ: a ≤ x < b}

(a, b]

the interval {{x ∈ ℝ: a < x ≤ b}

(a,b)

the open interval {x ∈ ℝ: a < x < b}