Benoît Bertrand ; Erwan Brugallé ; Arthur Renaudineau - Haas' theorem revisited

epiga:2030 - Épijournal de Géométrie Algébrique, September 1, 2017, Volume 1 -
Haas' theorem revisitedArticle

Authors: Benoît Bertrand ; Erwan Brugallé ; Arthur Renaudineau

    Haas' theorem describes all partchworkings of a given non-singular plane tropical curve $C$ giving rise to a maximal real algebraic curve. The space of such patchworkings is naturally a linear subspace $W_C$ of the $\mathbb{Z}/2\mathbb{Z}$-vector space $\overrightarrow \Pi_C$ generated by the bounded edges of $C$, and whose origin is the Harnack patchworking. The aim of this note is to provide an interpretation of affine subspaces of $\overrightarrow \Pi_C $ parallel to $W_C$. To this purpose, we work in the setting of abstract graphs rather than plane tropical curves. We introduce a topological surface $S_\Gamma$ above a trivalent graph $\Gamma$, and consider a suitable affine space $\Pi_\Gamma$ of real structures on $S_\Gamma$ compatible with $\Gamma$. We characterise $W_\Gamma$ as the vector subspace of $\overrightarrow \Pi_\Gamma$ whose associated involutions induce the same action on $H_1(S_\Gamma,\mathbb{Z}/2\mathbb{Z})$. We then deduce from this statement another proof of Haas' original result.

    Volume: Volume 1
    Published on: September 1, 2017
    Accepted on: August 3, 2017
    Submitted on: September 1, 2017
    Keywords: Mathematics - Algebraic Geometry,14P25, 14T05

    Consultation statistics

    This page has been seen 679 times.
    This article's PDF has been downloaded 633 times.