2.14 Variants

There is a more explicit syntax for specifying the number system the coefficients belong to. Rather than specifying a single number system which is used for all coefficients, a particular number system can be specified for each coefficient:

Some systems will require that the upper and lower coefficients are identical:

Such a requirement will render the presented systems impotent. The system

is not impotent; it is, in fact, similar to .

The free variables may be specified explicitly, as follows:

Hansen's   generalized interval arithmetic [28] can be succinctly stated as:

Jeff Tupper

March 1996