We analyse conditions for an evolution equation with a drift and fractional
diffusion to have a Holder continuous solution. In case the diffusion is of
order one or more, we obtain Holder estimates for the solution for any bounded
drift. In the case when the diffusion is of order less than one, we require the
drift to be a Holder continuous vector field in order to obtain the same type
of regularity result.Comment: some typos fixe
