Line transversals to disjoint balls
Ciprian S. Borcea, Xavier Goaoc, Sylvain Petitjean · 2007
We prove that the set of directions of lines intersecting three disjoint balls in R3 in a given order is a strictly convex subset of S2. We then generalize this result to n disjoint balls in Rd. As a consequence, we can improve upon several old and new results on line transversals to disjoint balls in arbitrary dimension, such as bounds on the number of connected components and Helly-type theorems.