Sobolev mappings on metric spaces and Minkowski dimension

We introduce the class of compactly Hölder mappings between metric spaces and determine the extent to which they distort the Minkowski dimension of a given set. These mappings are defined purely with metric notions and can be seen as a generalization of Sobolev mappings, without the requirement for a measure on the source space. In fact, we show that if $f:X\to Y$ is a continuous mapping lying in some super-critical Newtonian-Sobolev space $N^{1,p}(X,\mu )$, under standard assumptions on the metric measure space $(X,d,\mu )$, it is then a compactly Hölder mapping. The dimension distortion result we obtain is new even for Sobolev mappings between weighted Euclidean spaces and generalizes previous results of Kaufman and Bishop-Hakobyan-Williams.