On the computation of the topology of plane curves

Daouda Niang Diatta (1) , Fabrice Rouillier (2, 3) , Marie-Françoise Roy (4)

1 UASZ - Université Assane Seck de Ziguinchor [Sénégal]
2 IMJ - Institut de Mathématiques de Jussieu
3 OURAGAN - OUtils de Résolution Algébriques pour la Géométrie et ses ApplicatioNs
4 IRMAR - Institut de Recherche Mathématique de Rennes

Let P be a square free bivariate polynomial of degree at most d and with integer coefficients of bit size at most t. We give a deterministic algorithm for the computation of the topology of the real algebraic curve definit by P, i.e. a straight-line planar graph isotopic to the curve. Our main result is an algorithm for the computation of the local topology in a neighbourhood of each of the singular and critical points of the projection wrt the X axis in $\tilde{O} (d^6 t)$ bit operations where $\tilde{O}$ means that we ignore logarithmic factors in $d$ and $t$. Combined to state of the art sub-algorithms used for computing a Cylindrical Algebraic Decomposition, this result avoids a generic shear and gives a deterministic algorithm for the computation of the topology of the curve in $\tilde{O} (d^6 t + d^7)$ bit operations.

Mots clés: Calcul exact de topologie; Exact Topology Computation; Algebraic Curves; Courbes algébriques

Domaines: Géométrie algébrique [math.AG]; Calcul formel [cs.SC]

Daouda Niang Diatta, Fabrice Rouillier, Marie-Françoise Roy. On the computation of the topology of plane curves. International Symposium on Symbolic and Algebraic Computation, Kobe University, Jul 2014, Kobe, Japan. pp.130-137, ⟨10.1145/2608628.2608670⟩. ⟨hal-00935728v2⟩