Cardinal Invariants Associated with Hausdorff Capacities

Let λ(X) denote Lebesgue measure. If X ⊆ [0, 1] and r ∈ (0, 1) then the r-Hausdorff capacity of X is denoted by H(X) and is defined to be the infimum of all ∑ ∞ i=0 λ(Ii) r where {Ii}i∈ω is a cover of X by intervals. The r Hausdorff capacity has the same null sets as the r-Hausdorff measure which is familiar from the theory of fractal dimension. It is shown that, given r < 1, it is possible to enlarge a model of set theory, V , by a generic extension V [G] so that the reals of V have Lebesgue measure zero but still have positive r-Hausdorff capacity.