For intervals in the 
space there are two representation variants, for proper intervals and for singleton intervals.
For a singleton interval, where 
a single value is represented in brackets. Examples include [8.3], [8].
For normal intervals, the infinimum and supremum are written in brackets, separated by a comma. Examples
include [8.3,12.2], [8,12.6].
Empty intervals can be specified as both a singleton or a normal interval with instead of numbers the string nan.
Examples include: [nan] and [nan,nan].
Whole or unbound intervals can be specified with the corresponding element matching the string inf. Examples
include: [-inf, 3] and [-inf,inf]. Note that [inf] will result in an empty interval.