Constrained Triangulations, Volumes of Polytopes, and Unit Equations

Authors Michael Kerber, Robert Tichy, Mario Weitzer

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Michael Kerber
Robert Tichy
Mario Weitzer

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Michael Kerber, Robert Tichy, and Mario Weitzer. Constrained Triangulations, Volumes of Polytopes, and Unit Equations. In 33rd International Symposium on Computational Geometry (SoCG 2017). Leibniz International Proceedings in Informatics (LIPIcs), Volume 77, pp. 46:1-46:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2017)


Given a polytope P in R^d and a subset U of its vertices, is there a triangulation of P using d-simplices that all contain U? We answer this question by proving an equivalent and easy-to-check combinatorial criterion for the facets of P. Our proof relates triangulations of P to triangulations of its "shadow", a projection to a lower-dimensional space determined by U. In particular, we obtain a formula relating the volume of P with the volume of its shadow. This leads to an exact formula for the volume of a polytope arising in the theory of unit equations.
  • constrained triangulations
  • simplotopes
  • volumes of polytopes
  • projections of polytopes
  • unit equations
  • S-integers


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