Reconfiguration of Polygonal Subdivisions via Recombination

Authors Hugo A. Akitaya , Andrei Gonczi , Diane L. Souvaine , Csaba D. Tóth , Thomas Weighill

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Author Details

Hugo A. Akitaya
  • University of Massachusetts Lowell, MA, USA
Andrei Gonczi
  • Tufts University, Medford, MA, USA
Diane L. Souvaine
  • Tufts University, Medford, MA, USA
Csaba D. Tóth
  • California State University Northridge, Los Angeles, CA, USA
  • Tufts University, Medford, MA, USA
Thomas Weighill
  • University of North Carolina Greensboro, NC, USA

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Hugo A. Akitaya, Andrei Gonczi, Diane L. Souvaine, Csaba D. Tóth, and Thomas Weighill. Reconfiguration of Polygonal Subdivisions via Recombination. In 31st Annual European Symposium on Algorithms (ESA 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 274, pp. 6:1-6:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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.

Subject Classification

ACM Subject Classification
  • Social and professional topics → Social engineering attacks
  • Theory of computation → Computational geometry
  • Theory of computation → Nonconvex optimization
  • configuration space
  • gerrymandering
  • polygonal subdivision
  • recombination


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