The DOMAIN is the set of four FIRST coordinates {3,2,4,1}
However it is customary to list them in order and remove any
duplications:
DOMAIN = {1,2,3,4}
The RANGE is the set of all four second coordinates: (1,4,4,5}
However it is customary to list them in order and remove any
duplications:
RANGE: {1,4,5}
Edwin