 For formula_39, this can be thought of as region bounded by a square or rectangle whose sides are parallel to the coordinate axes, depending on whether the width of the intervals are the same or not; likewise, for formula_40, this can be thought of as a region bounded by an axis-aligned cube or a rectangular cuboid.In higher dimensions, the Cartesian product of formula_35 intervals is bounded by an n-dimensional hypercube or hyperrectangle.A facet of such an interval formula_2 is the result of replacing any non-degenerate interval factor formula_43 by a degenerate interval consisting of a finite endpoint of formula_43.