A counterexample to a conjecture on linear systems on .
A GAP package for braid orbit computation and applications.
A new source of structured singular value decomposition problems.
A septic with 99 real nodes
A simplified proof of desingularization and applications.
This paper contains a short and simplified proof of desingularization over fields of characteristic zero, together with various applications to other problems in algebraic geometry (among others, the study of the behavior of desingularization of families of embedded schemes, and a formulation of desingularization which is stronger than Hironaka's). Our proof avoids the use of the Hilbert-Samuel function and Hironaka's notion of normal flatness: First we define a procedure for principalization of...
A standard basis approach to syzygies of canonical curves.
About the computation of the signature of surface singularities z N + g(x, y) = 0
In this article we describe our experiences with a parallel Singular implementation of the signature of a surface singularity defined by z N + g(x; y) = 0.
About the group law for the Jacobi variety of a hyperelliptic curve.
Algorithmische P-Zerlegungen und Anwendungen
Algorithms for the computation of moduli spaces for semiquasihomogeneous singularities.
We present algorithms and their implementation in the computer algebra system Singular 2.0 for the computation of equations for moduli spaces for semiquasihomogeneous singularities w.r.t. right equivalence. In addition, we describe the structure of the stabilizer group of Brieskorn-Pham singularities.
An Algebraic Formula for the Index of a Vector Field on an Isolated Complete Intersection Singularity
Let be a germ of a complete intersection variety in , , having an isolated singularity at and be the germ of a holomorphic vector field having an isolated zero at and tangent to . We show that in this case the homological index and the GSV-index coincide. In the case when the zero of is also isolated in the ambient space we give a formula for the homological index in terms of local linear algebra.
An Algorithm for Lifting Points in a Tropical Variety
An algorithmic criterion for basicness in dimension 2.
An example of an arithmetic Fuchsian group.
Approximate implicitization of parametric curves using cubic algebraic splines.
Bornes pour la régularité de Castelnuovo-Mumford des schémas non lisses
Nous montrons dans cet article des bornes pour la régularité de Castelnuovo-Mumford d’un schéma admettant des singularités, en fonction des degrés des équations définissant le schéma, de sa dimension et de la dimension de son lieu singulier. Dans le cas où les singularités sont isolées, nous améliorons la borne fournie par Chardin et Ulrich et dans le cas général, nous établissons une borne doublement exponentielle en la dimension du lieu singulier.
Bounds on degrees of projective schemes.
Bouquets of circles for lamination languages and complexities
Laminations are classic sets of disjoint and non-self-crossing curves on surfaces. Lamination languages are languages of two-way infinite words which code laminations by using associated labeled embedded graphs, and which are subshifts. Here, we characterize the possible exact affine factor complexities of these languages through bouquets of circles, i.e. graphs made of one vertex, as representative coding graphs. We also show how to build families of laminations together with corresponding lamination...
Calcolo del conduttore di curve algebriche e ideali di punti
Calcul du nombre de points sur une courbe elliptique dans un corps fini : aspects algorithmiques
Nous décrivons dans cet article les algorithmes nécessaires à une implantation efficace de la méthode de Schoof pour le calcul du nombre de points sur une courbe elliptique dans un corps fini. Nous tentons d’unifier pour cela les idées d’Atkin et d’Elkies. En particulier, nous décrivons le calcul d’équations pour , premier, ainsi que le calcul efficace de facteurs des polynômes de division d’une courbe elliptique.