| ℕ* | set of natural numbers: ℕ* = {0, 1, 2,…} |
| ℕ | set of non-zero natural numbers: ℕ = {1, 2,…} |
| ℤ | set of integers: ℤ = {…,−2, −1,0, 1, 2,…} |
| ℚ | set of rational numbers |
| ℝ | space of real numbers |
| [[m, n]] | integer interval: [[m, n]] = {i ∈ ℕ* : m ≤ i ≤ n} |
| [[m, ∞]] | extended integer interval: [[m, ∞]] = {i ∈ ℕ* : i ≥ m} ⋃ {∞} |
| (a,b) | open interval: (a, b) = {x ∈ ℝ : a < x < b} |
| [a,b] | closed interval: [a, b] = {x ∈ ℝ : a ≤ x ≤ b} |
| ⋐ | compact inclusion in ℝd |
| ⊂ | algebraic inclusion |
| \ | set difference: U \ V = {u ∈ U : u∉ V} |
| × | product: U × V = {(u, υ) : u ∈ U, υ ∈ V} |
| ø | empty set |
