Zahorski theorem
From Wikipedia, the free encyclopedia
In mathematics, Zahorski's theorem is a theorem of real analysis. It states that a necessary and sufficient condition for a subset of the real line to be the set of points of non-differentiability of a continuous real-valued function, is that it be the union of a Gδ set and a 
set of zero measure.
This result was proved by Zygmunt Zahorski in 1939 and first published in 1941.
[edit] References
- Sur l'ensemble des points de non-derivabilite d'une fonction continue, Zygmunt Zahorski, Bulletin de la Société Mathématique de France 74 (1946), p. 147-178
