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A Universal Triangulation for Flat Tori

Authors Francis Lazarus, Florent Tallerie

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Author Details

Francis Lazarus
  • G-SCOP, CNRS, UGA, Grenoble, France
Florent Tallerie
  • G-SCOP, UGA, Grenoble, France


We warmly thank Alba Málaga, Pierre Arnoux and Samuel Lelièvre for sharing with us their constructions of flat tori and showing us how to cover their moduli space with these constructions. We are also grateful to the anonymous reviewers for their careful reading and suggestions.

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Francis Lazarus and Florent Tallerie. A Universal Triangulation for Flat Tori. In 38th International Symposium on Computational Geometry (SoCG 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 224, pp. 53:1-53:18, Schloss Dagstuhl - Leibniz-Zentrum für Informatik (2022)


A result due to Burago and Zalgaller states that every orientable polyhedral surface, one that is obtained by gluing Euclidean polygons, has an isometric piecewise linear (PL) embedding into Euclidean space 𝔼³. A flat torus, resulting from the identification of the opposite sides of a Euclidean parallelogram, is a simple example of polyhedral surface. In a first part, we adapt the proof of Burago and Zalgaller, which is partially constructive, to produce PL isometric embeddings of flat tori. In practice, the resulting embeddings have a huge number of vertices, moreover distinct for every flat torus. In a second part, based on another construction of Zalgaller and on recent works by Arnoux et al., we exhibit a universal triangulation with 5974 triangles which can be embedded linearly on each triangle in order to realize the metric of any flat torus.

Subject Classification

ACM Subject Classification
  • Mathematics of computing → Geometric topology
  • Mathematics of computing → Discrete mathematics
  • Theory of computation → Computational geometry
  • Triangulation
  • flat torus
  • isometric embedding


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