ABSTRACT
A point of Rk is denoted (x1, x2, . . . , xk). In the analysis of functions of one real variable, the domain of a function is typically an open interval. Since any open set in R1 is the disjoint union of open intervals, it is natural to work in the context of intervals. Such a simple situation does not obtain in the analysis of several variables. We will need some new notation and concepts in order to study functions in Rk.
