Linearidade em conjuntos de funções contínuas que não são diferenciáveis em nenhum ponto

Abstract

In this work we study in detail the set of nowhere differentiable continuous functions. We start constructing an example of such function due to van der Waerden and we prove that the set ND[0,1] of such functions is large in C[0,1], in the sense of Baire category. We also prove that ND[0,1] is spaceable and, moreover, the separable Banach spaces can be seen as subspaces of C[0,1]. Finally, we prove that the set of nowhere Hölder functions is dense-algebrable and in particular we obtain that ND[0,1] is algebrable.