In this article we introduce some definitions concerning measurable functions and prove related properties. In this paper k is a natural number, r is a real number, i is an integer, and q is a rational number. The subset Z − of R is defined by: (Def. 1) r ∈ Z − iff there exists k such that r = −k. Let us note that Z − is non empty. The following three propositions are true: (1) N ≈ Z −. Z is a ...
