Paper #941

Títol:

Riesz-Nágy singular functions revisited

Autors:

Jaume Paradís, Pelegrí Viader i Lluís Bibiloni

Data:

Febrer 2006

Resum:

In 1952 F. Riesz and Sz.N�gy published an example of a monotonic continuous function whose derivative is zero almost everywhere, that is to say, a singular function. Besides, the function was strictly increasing. Their example was built as the limit of a sequence of deformations of the identity function. As an easy consequence of the definition, the derivative, when it existed and was finite, was found to be zero. In this paper we revisit the Riesz-N�agy family of functions and we relate it to a system for real number representation which we call (t, t-1)�expansions. With the help of these real number expansions we generalize the family. The singularity of the functions is proved through some metrical properties of the expansions used in their definition which also allows us to give a more precise way of determining when the derivative is 0 or infinity.

Paraules clau:

Singular functions, metric number theory

Codis JEL:

C00

Àrea de Recerca:

Estadística, Econometria i Mètodes Quantitatius

Publicat a:

Journal of Mathematical Analysis and its Applications, 329, 1, pp. 592-602, August 2007

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