Threshold Dynamics of Voter Radicalization on the Probability Simplex

Fuente: arXiv
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Autor principal: Omelchenko, Alexander
Formato: Preprint
Publicado: 2026
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author Omelchenko, Alexander
author_facet Omelchenko, Alexander
contents We analyse two coupled ODE models of political competition on invariant probability simplices with a conserved electorate. The baseline three-group model tracks left-radical, centrist, and right-radical voter shares. We characterise the unique interior equilibrium by a Perron--Frobenius threshold, establish global asymptotic stability in the symmetric and asymmetric cases, and exclude periodic orbits unconditionally via the Dulac criterion. A structural consequence is that the baseline model cannot produce irreversible centrist decline, history-dependent long-run floors, or multiple attractors. We then extend the model with a disengaged voter compartment and distinguish pure state shocks from permanent structural parameter shifts. The post-shock dynamics are governed by the same spectral threshold: below it the centrist state is globally asymptotically stable; above it every trajectory with a nonzero radical seed converges to the unique radicalised equilibrium. Cumulative sub-threshold structural shifts can cross the threshold and produce staircase dynamics absent from the baseline; the symmetric reduction yields closed-form expressions for the critical shock amplitude and the radicalization window.
format Preprint
id arxiv_https___arxiv_org_abs_2603_07862
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Threshold Dynamics of Voter Radicalization on the Probability Simplex
Omelchenko, Alexander
Dynamical Systems
34D23, 34C23, 37C75, 37N40, 91B14
We analyse two coupled ODE models of political competition on invariant probability simplices with a conserved electorate. The baseline three-group model tracks left-radical, centrist, and right-radical voter shares. We characterise the unique interior equilibrium by a Perron--Frobenius threshold, establish global asymptotic stability in the symmetric and asymmetric cases, and exclude periodic orbits unconditionally via the Dulac criterion. A structural consequence is that the baseline model cannot produce irreversible centrist decline, history-dependent long-run floors, or multiple attractors. We then extend the model with a disengaged voter compartment and distinguish pure state shocks from permanent structural parameter shifts. The post-shock dynamics are governed by the same spectral threshold: below it the centrist state is globally asymptotically stable; above it every trajectory with a nonzero radical seed converges to the unique radicalised equilibrium. Cumulative sub-threshold structural shifts can cross the threshold and produce staircase dynamics absent from the baseline; the symmetric reduction yields closed-form expressions for the critical shock amplitude and the radicalization window.
title Threshold Dynamics of Voter Radicalization on the Probability Simplex
topic Dynamical Systems
34D23, 34C23, 37C75, 37N40, 91B14
url https://arxiv.org/abs/2603.07862