Unimodular triangulations of dilated 3-polytopes

Abstract

A seminal result in the theory of toric varieties, due to Knudsen, Mumford and Waterman (1973), asserts that for every lattice polytope $P$ there is a positive integer $k$ such that the dilated polytope $kP$ has a unimodular triangulation. In dimension 3, Kantor and Sarkaria (2003) have shown that $k=4$ works for every polytope. But this does not imply that every $k>4$ works as well. We here study the values of $k$ for which the result holds showing that: 1. It contains all composite numbers. 2. It is an additive semigroup. These two properties imply that the only values of $k$ that may not work (besides 1 and 2, which are known not to work) are $k\in \{3,5,7,11\}$. With an ad-hoc construction we show that $k=7$ and $k=11$ also work, except in this case the triangulation cannot be guaranteed to be "standard" in the boundary. All in all, the only open cases are $k=3$ and $k=5$.

23 pages, 17 figures

References in corpus (1)

• Clean Lattice Tetrahedra

Cited by in corpus (8)

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• Ehrhart-equivalent $3$-polytopes are equidecomposable
• Ehrhart-Equivalence, Equidecomposability, and Unimodular Equivalence of Integral Polytopes
• Unimodular covers of 3-dimensional parallelepipeds and Cayley sums