Motivated by the problem of redistricting, we study area-preserving reconfigurations of connected subdivisions of a simple polygon. A connected subdivision of a polygon ℛ, called a district map, is a set of interior disjoint connected polygons called districts whose union equals ℛ. We consider the recombination as the reconfiguration move which takes a subdivision and produces another by merging two adjacent districts, and by splitting them into two connected polygons of the same area as the original districts. The complexity of a map is the number of vertices in the boundaries of its districts. Given two maps with k districts, with complexity O(n), and a perfect matching between districts of the same area in the two maps, we show constructively that (log n)^O(log k) recombination moves are sufficient to reconfigure one into the other. We also show that Ω(log n) recombination moves are sometimes necessary even when k = 3, thus providing a tight bound when k = 3.
@InProceedings{a.akitaya_et_al:LIPIcs.ESA.2023.6, author = {A. Akitaya, Hugo and Gonczi, Andrei and Souvaine, Diane L. and T\'{o}th, Csaba D. and Weighill, Thomas}, title = {{Reconfiguration of Polygonal Subdivisions via Recombination}}, booktitle = {31st Annual European Symposium on Algorithms (ESA 2023)}, pages = {6:1--6:16}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-295-2}, ISSN = {1868-8969}, year = {2023}, volume = {274}, editor = {G{\o}rtz, Inge Li and Farach-Colton, Martin and Puglisi, Simon J. and Herman, Grzegorz}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2023.6}, URN = {urn:nbn:de:0030-drops-186598}, doi = {10.4230/LIPIcs.ESA.2023.6}, annote = {Keywords: configuration space, gerrymandering, polygonal subdivision, recombination} }
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