Metric spaces and mappings

Abstract

In Chapters 2 through 5 we developed many properties of functions from ℝ₁ into ℝ₁ with the purpose of proving the basic theorems in differential and integral calculus of one variable. The next step in analysis is the establishment of the basic facts needed in proving the theorems of calculus in two and more variables. One way would be to prove extensions of the theorems of Chapters 2–5 for functions from ℝ₂ in to ℝ₁ then for functions from ℝ₃ into ℝ₁, and so forth. However, all these results can be encompassed in one general theory obtained by introducing the concept of a metric space and by considering functions defined on one metric space with range in a second metric space. In this chapter we introduce the fundamentals of this theory and in the following two chapters the results are applied to differentiation and integration in Euclidean space in any number of dimensions.