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arXiv · 2509.09520

Unstable entropy for Anosov diffeomorphisms on the 3-torus

Tristan Humbert
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Abstract

For Anosov diffeomorphisms on the $3$-torus which are strongly partially hyperbolic with expanding center, we construct systems of strong unstable and center stable Margulis measures which are holonomy-invariant. This allows us to obtain a characterization of the measures of maximal unstable entropy in terms of their conditional measures along the strong unstable leaves. Moreover, we show that the Margulis systems identify with Pollicott-Ruelle (co)-resonant states for the action on 2-forms. This shows that the unstable topological entropy and a measure of maximal unstable entropy can be retrieved from the spectral approach.

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Tristan Humbert. 2025-09-11. Unstable entropy for Anosov diffeomorphisms on the 3-torus. https://arxiv.org/abs/2509.09520

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