The triangular metric on projective surfaces
Abstract
In \cite{ThurstonStretch} Thurston introduced stretch paths and stretch maps between hyperbolic surfaces. In this paper we extend similar constructions to the space of convex real projective structures on surfaces. Using Fock-Goncharov-like parameters, we introduce stretch paths and construct explicit stretch maps between the projective surface. We show that stretch maps are et--Lipschitz with respect to a triangular metric we introduce on the projective surface. This allows us to gain control on several length functions on an open set of the space of convex real projective structures (those where there is no ``local back--tracking"). As an application we obtain pointwise upper bounds for the Hilbert entropy of some convex real projective structures in terms of Fock-Goncharov-like parameters.
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BibTeX
@misc{carvajales2026triangular,
title = {{The triangular metric on projective surfaces}},
author = {León Carvajales and Xian Dai and Beatrice Pozzetti and Anna Wienhard},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.16487},
eprint = {2610.16487},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.16487},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - The triangular metric on projective surfaces
AU - León Carvajales
AU - Xian Dai
AU - Beatrice Pozzetti
AU - Anna Wienhard
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2610.16487
UR - https://arxiv.org/abs/2610.16487
AB - In \cite{ThurstonStretch} Thurston introduced stretch paths and stretch maps between hyperbolic surfaces. In this paper we extend similar constructions to the space of convex real projective structures on surfaces. Using Fock-Goncharov-like parameters, we introduce stretch paths and construct explicit stretch maps between the projective surface. We show that stretch maps are e^t--Lipschitz with respect to a triangular metric we introduce on the projective surface. This allows us to gain control on several length functions on an open set of the space of convex real projective structures (those where there is no ``local back--tracking"). As an application we obtain pointwise upper bounds for the Hilbert entropy of some convex real projective structures in terms of Fock-Goncharov-like parameters.
ER -