One sided extendability and p-continuous analytic capacities

Using complex methods combined with Baires Theorem we show that one-sided extendability, extendability and real analyticity are rare phenomena on various spaces of functions in the topological sense. These considerations led us to introduce the p-continuous analytic capacity and variants of it, $p in { 0, 1, 2, cdots } cup { infty }$, for compact or closed sets in $mathbb{C}$. We use these capacities in order to characterize the removability of singularities of functions in the spaces $A^p$.