PreprintCC BY 4.0arXiv
Enumerating Integral Points on Triangles in ℝ3
Abstract
We present two ways of constructing Ehrhart polynomials corresponding to certain triangles in ℝ3. One of our methods employs Popoviciu's Theorem, while the other method uses a version of Pick's Theorem adapted to rank-2 lattices in ℝ3. We then apply our methods to linear Diophantine equations of the form ax+by+cz=n and develop upper and lower bounds on the number of solutions in nonnegative integers x, y, and z. The bounds we develop are closed form quasi-polynomials, and the difference between them is bounded by a constant depending only on a and b. As an application, we prove that the kth Frobenius number exists for any triple of positive integers and any k.
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BibTeX
@misc{aldrich2026enumerating,
title = {{Enumerating Integral Points on Triangles in $\mathbbR^3$}},
author = {Max Aldrich and Daniel Gulbrandsen and Clara Keddy},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.20899},
eprint = {2610.20899},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.20899},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Enumerating Integral Points on Triangles in ℝ^3
AU - Max Aldrich
AU - Daniel Gulbrandsen
AU - Clara Keddy
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.20899
UR - https://arxiv.org/abs/2610.20899
AB - We present two ways of constructing Ehrhart polynomials corresponding to certain triangles in ℝ^3. One of our methods employs Popoviciu's Theorem, while the other method uses a version of Pick's Theorem adapted to rank-2 lattices in ℝ^3. We then apply our methods to linear Diophantine equations of the form ax+by+cz=n and develop upper and lower bounds on the number of solutions in nonnegative integers x, y, and z. The bounds we develop are closed form quasi-polynomials, and the difference between them is bounded by a constant depending only on a and b. As an application, we prove that the kth Frobenius number exists for any triple of positive integers and any k.
ER -