Some New Results on Geometric Transversals

Abstract

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 \(\varepsilon \)-nets for k-flats and convex sets in \(\mathbb {R}^d\), 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 \(\mathbb {R}^3\), and we extend a theorem of Karasev and Montejano regarding colorful intersections and k-transversals.