A general mass transference principle

The Mass Transference Principle proved by Beresnevich and Velani (Ann. Math. (2) 164(3):971–992, 2006 ) is a celebrated and highly influential result which allows us to infer Hausdorff measure statements for lim sup sets of balls in R n from a priori weaker Lebesgue measure statements. The Mass Transference Principle and subsequent generalisations have had a profound impact on several areas of mathematics, especially Diophantine Approximation. In the present paper, we prove a considerably more general form of the Mass Transference Principle which extends known results of this type in several distinct directions. In particular, we establish a Mass Transference Principle for lim sup sets defined via neighbourhoods of sets satisfying a certain local scaling property. Such sets include self-similar sets satisfying the open set condition and smooth compact manifolds embedded in R n . Furthermore, our main result is applicable in locally compact metric spaces and allows one to transfer Hausdorff g -measure statements to Hausdorff f -measure statements. We conclude the paper with an application of our mass transference principle to a general class of random lim sup sets.