The colorful Helly theorem and Tverberg’s theorem are fundamental results in discrete geometry. We prove a theorem which interpolates between the two. In particular, we show the following for any integers d ≥ m ≥ 1 and k a prime power. Suppose F₁, F₂, … , F_m are families of convex sets in ℝ^d, each of size n > (d/m+1)(k-1), such that for any choice C_i ∈ F_i we have ⋂_{i = 1}^m C_i ≠ ∅. Then, one of the families F_i admits a Tverberg k-partition. That is, one of the F_i can be partitioned into k nonempty parts such that the convex hulls of the parts have nonempty intersection. As a corollary, we also obtain a result concerning r-dimensional transversals to families of convex sets in ℝ^d that satisfy the colorful Helly hypothesis, which extends the work of Karasev and Montejano.
@InProceedings{dobbins_et_al:LIPIcs.SoCG.2024.52, author = {Dobbins, Michael Gene and Holmsen, Andreas F. and Lee, Dohyeon}, title = {{Colorful Intersections and Tverberg Partitions}}, booktitle = {40th International Symposium on Computational Geometry (SoCG 2024)}, pages = {52:1--52:13}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-316-4}, ISSN = {1868-8969}, year = {2024}, volume = {293}, editor = {Mulzer, Wolfgang and Phillips, Jeff M.}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2024.52}, URN = {urn:nbn:de:0030-drops-199973}, doi = {10.4230/LIPIcs.SoCG.2024.52}, annote = {Keywords: Tverberg’s theorem, geometric transversals, topological combinatorics, configuration space/test map, discrete Morse theory} }
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