## ABSTRACT

Let us begin with the following elementary observation. Consider a differentiable function ƒ: ℝ → ℝ. Then the condition f′ ≠ 0 a.e. is both necessary and sufficient to insure that the measure on ℝ induced by f is absolutely continuous with respect to the Lebesgue measure. Similar result holds also for distributions of functionals on finite dimensional Euclidean space ℝ
^{n}
.