## Detailed description

Diagram showing all combinations of open and closed intervals. [a, b] is the closed interval from a to b.

- [a, b) is the interval from a, included to b, not included.
- (a, b] is the interval from a, not included to b, included.
- (-infinity, a) is the interval of all numbers to the left of a with a not included.
- (-infinity, a] is the interval of all numbers to the left of a with a included.
- (b, infinity) is the set of all numbers to the right of b not including b.
- [b, infinity) is the set of all numbers to the right of b including b.
- (-infinity, infinity) is the set of all real numbers R.