Let denote a two-dimensional linear interval arithmetic, such as or . We will not ensure that R represents directly; we will instead work with . The interval specification is computed by evaluating the specification S using the interval arithmetic . The interval inclusion property assures us that
Other linear interval arithmetics may be used, such as or , given an appropriate . Better renderings may be obtained by taking S into account when choosing and .
Jeff Tupper | March 1996 |