Fast Isotopy Computation for T-Curves

Fuente: arXiv
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Hauptverfasser: Geiselmann, Zoe, Joswig, Michael, Kastner, Lars, Mundinger, Konrad, Pokutta, Sebastian, Spiegel, Christoph, Wack, Marcel, Zimmer, Max
Format: Preprint
Veröffentlicht: 2026
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author Geiselmann, Zoe
Joswig, Michael
Kastner, Lars
Mundinger, Konrad
Pokutta, Sebastian
Spiegel, Christoph
Wack, Marcel
Zimmer, Max
author_facet Geiselmann, Zoe
Joswig, Michael
Kastner, Lars
Mundinger, Konrad
Pokutta, Sebastian
Spiegel, Christoph
Wack, Marcel
Zimmer, Max
contents A T-curve of degree $d$ is given by a regular unimodular triangulation of $d \cdot Δ_2$ together with a sign distribution on its lattice points. By Viro's Patchworking Theorem, this determines the ambient isotopy type (a.k.a. real scheme) of a smooth real plane projective algebraic curve of the same degree. We present a near-quadratic time algorithm for extracting that isotopy type from the triangulation and the signs. Through a GPU-accelerated implementation, this allows one to compute billions of real schemes per second, enabling exhaustive enumeration at scale. This algorithm was essential for our recent construction of all 121 real schemes of degree seven by T-curves.
format Preprint
id arxiv_https___arxiv_org_abs_2604_09221
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Fast Isotopy Computation for T-Curves
Geiselmann, Zoe
Joswig, Michael
Kastner, Lars
Mundinger, Konrad
Pokutta, Sebastian
Spiegel, Christoph
Wack, Marcel
Zimmer, Max
Algebraic Geometry
Computational Geometry
Combinatorics
14P25, 14Q05, 14Q30, 52B20
A T-curve of degree $d$ is given by a regular unimodular triangulation of $d \cdot Δ_2$ together with a sign distribution on its lattice points. By Viro's Patchworking Theorem, this determines the ambient isotopy type (a.k.a. real scheme) of a smooth real plane projective algebraic curve of the same degree. We present a near-quadratic time algorithm for extracting that isotopy type from the triangulation and the signs. Through a GPU-accelerated implementation, this allows one to compute billions of real schemes per second, enabling exhaustive enumeration at scale. This algorithm was essential for our recent construction of all 121 real schemes of degree seven by T-curves.
title Fast Isotopy Computation for T-Curves
topic Algebraic Geometry
Computational Geometry
Combinatorics
14P25, 14Q05, 14Q30, 52B20
url https://arxiv.org/abs/2604.09221