Some New Results on Geometric Transversals

We investigate a number of questions, problems, and conjectures related to geometric transversal theory. Among our results we disprove a conjecture of Bárány and Kalai regarding weak ε -nets for k -flats and convex sets in ℝ^d , and we prove a conjecture of Arocha, Bracho, and Montejano regarding a colorful version of the Goodman–Pollack–Wenger transversal theorem. We also investigate the connected components of the space of line transversals to pairwise disjoint convex sets in ℝ^3 , and we extend a theorem of Karasev and Montejano regarding colorful intersections and k -transversals.