A transversality theorem for multiple-point crossings under generic linear perturbations with Hausdorff measure estimates

Abstract

We establish a transversality theorem for multiple-point crossings under generic linear perturbations with explicit Hausdorff measure estimates for the exceptional parameter set, and hence explicit upper bounds on its Hausdorff dimension. This strengthens our earlier result, which showed only that the exceptional parameter set has Lebesgue measure zero. As applications, we obtain results on normal crossings, injectivity, and embeddings under generic linear perturbations. The embedding result yields a refinement of Mather's stability theorem for generic projections when the target dimension is more than twice the source dimension, with an explicit upper bound on the Hausdorff dimension of the exceptional set.