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

epiga:2030 - Épijournal de Géométrie Algébrique, 1 septembre 2017, Volume 1 - https://doi.org/10.46298/epiga.2017.volume1.2030
Haas' theorem revisitedArticle

Auteurs : 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
    Publié le : 1 septembre 2017
    Accepté le : 3 août 2017
    Soumis le : 1 septembre 2017
    Mots-clés : Mathematics - Algebraic Geometry,14P25, 14T05

    Statistiques de consultation

    Cette page a été consultée 644 fois.
    Le PDF de cet article a été téléchargé 609 fois.