Since we will be discussing floating point numbers further, it
will be useful to have an abstract model of floating
point numbers. That model is the extended real number
system, 
:
There is a natural homomorphism 
from the floats to the extended reals.
There is another natural homomorphism 
from the reals to the extended reals.
These homomorpisms allow for comparisons and operations to be applied
between floats and reals by type promotion.
| Jeff Tupper | March 1996 |