Coxeter-Dynkin diagrams of the complete intersection singularities Z9 and Z10.
Critical and ramification points of the modular parametrization of an elliptic curve
Let be an elliptic curve defined over with conductor and denote by the modular parametrization:In this paper, we are concerned with the critical and ramification points of . In particular, we explain how we can obtain a more or less experimental study of these points.
Cubic differential forms and the group law on the Jacobian of a real algebraic curve
In an earlier paper [6], we gave an explicit geometric description of the group law on the neutral component of the set of real points of the Jacobian of a smooth quartic curve. Here, we generalize this description to curves of higher genus. We get a description of the group law on the neutral component of the set of real points of the Jacobian of a smooth curve in terms of cubic differential forms. When applied to canonical curves, one gets an explicit geometric description of this group law by...
Curvature on holomorphic plane curves. II
Curves and their fundamental groups
Curves in P² and symplectic packings.
Curves in P2(C) with 1-dimensional symmetry.
In a previous paper we showed that the existence of a 1-parameter symmetry group of a hypersurface X in projective space was equivalent to failure of versality of a certain unfolding. Here we study in detail (reduced) plane curves of degree d ≥ 3, excluding the trivial case of cones. We enumerate all possible group actions -these have to be either semisimple or unipotent- for any degree d. A 2-parameter group can only occur if d = 3. Explicit lists of singularities of the corresponding curves are...
Curves of
Curves of genus 2 and Desargues configurations.
Curves of genus 2, continued fractions, and Somos sequences.
Curves of genus g lying on a g-dimensional Jacobian variety.
Curves of genus seven that do not satisfy the Gieseker-Petri theorem
In the moduli space of curves of genus , , let be the locus of curves that do not satisfy the Gieseker-Petri theorem. In the genus seven case we show that is a divisor in .
Curves of genus ten on K3 surfaces
Curves of maximal genus in .
Curves of minimal genus on a general abelian variety
Curves on a double surface.
Let F be a smooth projective surface contained in a smooth threefold T, and let X be the scheme corresponding to the divisor 2F on T. A locally Cohen-Macaulay curve C included in X gives rise to two effective divisors on F, namely the largest divisor P contained in C intersection F and the curve R residual to C intersection F in C. We show that under suitable hypotheses a general deformation of R and P lifts to a deformation of C on X, and give applications to the study of Hilbert schemes of locally...
Curves on a ruled cubic surface.
For the general ruled cubic surface S (with a double line) in P3 = P3 sub k, k any algebraically closed field, we find necessary conditions for which curves on S can be the specialization of a flat family of curves on smooth cubics. In particular, no smooth curve of degree > 10 on S is such a specialization.
Curves on a smooth quadric.
We associate to every curve on a smooth quadric a polynomial equation that defines it as a divisor; this polynomial is defined through a matrix. In this way we can study several properties of these curves; in particular we can give a geometrical meaning to the rank of the matrix which defines the curve.
Curves on generic hypersurfaces
Curves on surfaces of degree 2r-... in Pr.