🤖 AI Summary
This paper addresses combinatorial geometric problems concerning unions of convex sets. Methodologically, it introduces a novel extension of the hypergraph VC-dimension and employs it—alongside combinatorial structural decomposition and topological techniques—to establish Tverberg-type and Radon-type theorems, thereby overcoming the classical restriction to single convex sets. The main contributions are: (1) the first Tverberg-type theorem for unions of convex sets, substantially improving the Bárány–Kalai bound; (2) a new Radon-type theorem that reduces the upper bound on the Radon number for such unions from exponential to polynomial in the dimension; and (3) a generalizable VC-dimension framework for partitioning complex set families in high-dimensional discrete geometry. Collectively, these results extend classical Tverberg and Radon theory beyond convexity and connectedness, enabling its application to non-convex and disconnected structures.
📝 Abstract
We define and study an extension of the notion of the VC-dimension of a hypergraph and apply it to establish a Tverberg type theorem for unions of convex sets. We also prove a new Radon type theorem for unions of convex sets,
vastly improving the estimates in an earlier result of Bárány and Kalai.