We prove a self-improving property for reverse H{\"o}lder inequalities with
non-local right hand side. We attempt to cover all the most important
situations that one encounters when studying elliptic and parabolic partial
differential equations as well as certain fractional equations. We also
consider non-local extensions of A∞ weights. We write our results in
spaces of homogeneous type.Comment: Revised version. Changed title. Application to a more relevant
fractional elliptic equation given in the final section. 40 page