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Main Authors: Çelik, Türkü Özlüm, Haas, Pierre A., Scholten, Georgy, Wang, Kexin, Zucal, Giulio
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2509.00165
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author Çelik, Türkü Özlüm
Haas, Pierre A.
Scholten, Georgy
Wang, Kexin
Zucal, Giulio
author_facet Çelik, Türkü Özlüm
Haas, Pierre A.
Scholten, Georgy
Wang, Kexin
Zucal, Giulio
contents We study the Lotka--Volterra system from the perspective of computational algebraic geometry, focusing on equilibria that are both feasible and stable. These conditions stratifies the parameter space in $\mathbb{R}\times\mathbb{R}^{n\times n}$ with the feasible-stable semialgebraic sets. We encode them on the real Grassmannian ${\rm Gr}_{\mathbb{R}}(n,2n)$ via a parameter matrix representation, and use oriented matroid theory to develop an algorithm, combining Grassmann--Pl{ü}cker relations with branching under feasibility and stability constraints. This symbolic approach determines whether a given sign pattern in the parameter space $\mathbb{R}\times\mathbb{R}^{n\times n}$ admits a consistent extension to Pl{ü}cker coordinates. As an application, we establish the impossibility of certain interaction networks, showing that the corresponding patterns admit no such extension satisfying feasibility and stability conditions, through an effective implementation. We complement these results using numerical nonlinear algebra with \texttt{HypersurfaceRegions.jl} to decompose the parameter space and detect rare feasible-stable sign patterns.
format Preprint
id arxiv_https___arxiv_org_abs_2509_00165
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Strata of Ecological Coexistence via Grassmannians
Çelik, Türkü Özlüm
Haas, Pierre A.
Scholten, Georgy
Wang, Kexin
Zucal, Giulio
Algebraic Geometry
We study the Lotka--Volterra system from the perspective of computational algebraic geometry, focusing on equilibria that are both feasible and stable. These conditions stratifies the parameter space in $\mathbb{R}\times\mathbb{R}^{n\times n}$ with the feasible-stable semialgebraic sets. We encode them on the real Grassmannian ${\rm Gr}_{\mathbb{R}}(n,2n)$ via a parameter matrix representation, and use oriented matroid theory to develop an algorithm, combining Grassmann--Pl{ü}cker relations with branching under feasibility and stability constraints. This symbolic approach determines whether a given sign pattern in the parameter space $\mathbb{R}\times\mathbb{R}^{n\times n}$ admits a consistent extension to Pl{ü}cker coordinates. As an application, we establish the impossibility of certain interaction networks, showing that the corresponding patterns admit no such extension satisfying feasibility and stability conditions, through an effective implementation. We complement these results using numerical nonlinear algebra with \texttt{HypersurfaceRegions.jl} to decompose the parameter space and detect rare feasible-stable sign patterns.
title Strata of Ecological Coexistence via Grassmannians
topic Algebraic Geometry
url https://arxiv.org/abs/2509.00165