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CG Challenge

DOI: 10.4230/LIPIcs.SoCG.2026.108

CG#Hunters Approach to Central Triangulation Under Parallel Flip Operations (CG Challenge)

Authors: Jaegun Lee, Seokyun Kang, Hyeonseok Lee, Hyeyun Yang, and Taehoon Ahn

Published in: LIPIcs, Volume 367, 42nd International Symposium on Computational Geometry (SoCG 2026)

Abstract

In the CG:SHOP 2026 Challenge, the goal is to compute a central triangulation for a given set of triangulations on the same point set while minimizing the sum of parallel flip distances. To address the problem, our team (CG#Hunters) constructs an initial solution by iteratively applying parallel flips to reduce the total number of crossings between the triangulations until none remain. To optimize these solutions, we shorten the paths by using a score-based greedy edge selection and refine the central triangulation via a large scale neighborhood search. Additionally, a representative-set-based approach is utilized to efficiently handle large instances. With these combined approaches, we achieved third place by successfully computing central triangulations with sufficiently short parallel flip paths for all 250 instances.

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Jaegun Lee, Seokyun Kang, Hyeonseok Lee, Hyeyun Yang, and Taehoon Ahn. CG#Hunters Approach to Central Triangulation Under Parallel Flip Operations (CG Challenge). In 42nd International Symposium on Computational Geometry (SoCG 2026). Leibniz International Proceedings in Informatics (LIPIcs), Volume 367, pp. 108:1-108:8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2026)

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@InProceedings{lee_et_al:LIPIcs.SoCG.2026.108,
  author =	{Lee, Jaegun and Kang, Seokyun and Lee, Hyeonseok and Yang, Hyeyun and Ahn, Taehoon},
  title =	{{CG#Hunters Approach to Central Triangulation Under Parallel Flip Operations}},
  booktitle =	{42nd International Symposium on Computational Geometry (SoCG 2026)},
  pages =	{108:1--108:8},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-418-5},
  ISSN =	{1868-8969},
  year =	{2026},
  volume =	{367},
  editor =	{Ahn, Hee-Kap and Hoffmann, Michael and Nayyeri, Amir},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2026.108},
  URN =		{urn:nbn:de:0030-drops-259147},
  doi =		{10.4230/LIPIcs.SoCG.2026.108},
  annote =	{Keywords: Central triangulation, Parallel flip operations, Crossing number, Large scale neighborhood search, Representative set}
}

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CG Challenge

DOI: 10.4230/LIPIcs.SoCG.2021.65

A Simulated Annealing Approach to Coordinated Motion Planning (CG Challenge)

Authors: Hyeyun Yang and Antoine Vigneron

Published in: LIPIcs, Volume 189, 37th International Symposium on Computational Geometry (SoCG 2021)

Abstract

The third computational geometry challenge was on a coordinated motion planning problem in which a collection of square robots need to move on the integer grid, from their given starting points to their target points, and without collision between robots, or between robots and a set of input obstacles. We designed and implemented an algorithm for this problem, which consists of three parts. First, we computed a feasible solution by placing middle-points outside of the minimum bounding box of the input positions of the robots and the obstacles, and moving each robot from its starting point to its target point through a middle-point. Second, we applied a simple local search approach where we repeatedly delete and insert again a random robot through an optimal path. It improves the quality of the solution, as the robots no longer need to go through the middle-points. Finally, we used simulated annealing to further improve this feasible solution. We used two different types of moves: We either tightened the whole trajectory of a robot, or we stretched it between two points by making the robot move through a third intermediate point generated at random.

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Hyeyun Yang and Antoine Vigneron. A Simulated Annealing Approach to Coordinated Motion Planning (CG Challenge). In 37th International Symposium on Computational Geometry (SoCG 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 189, pp. 65:1-65:9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)

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@InProceedings{yang_et_al:LIPIcs.SoCG.2021.65,
  author =	{Yang, Hyeyun and Vigneron, Antoine},
  title =	{{A Simulated Annealing Approach to Coordinated Motion Planning}},
  booktitle =	{37th International Symposium on Computational Geometry (SoCG 2021)},
  pages =	{65:1--65:9},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-184-9},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{189},
  editor =	{Buchin, Kevin and Colin de Verdi\`{e}re, \'{E}ric},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2021.65},
  URN =		{urn:nbn:de:0030-drops-138649},
  doi =		{10.4230/LIPIcs.SoCG.2021.65},
  annote =	{Keywords: Path planning, simulated annealing, local search}
}

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Documents authored by Yang, Hyeyun

CG#Hunters Approach to Central Triangulation Under Parallel Flip Operations (CG Challenge)

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A Simulated Annealing Approach to Coordinated Motion Planning (CG Challenge)

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