Curve equations from expansions of 1-forms at a nonrational point
Abstract
We exhibit an algorithm to compute equations of an algebraic curve over a computable characteristic 0 field from the power series expansions of its regular 1-forms at a nonrational point of the curve, extending a 2005 algorithm of Baker, González-Jiménez, González, and Poonen for expansions at a rational point. If the curve is hyperelliptic, the equations present it as an explicit double cover of a smooth plane conic, or as a double cover of the projective line when possible. If the curve is nonhyperelliptic, the equations cut out the canonical model. The algorithm has been used to compute equations over Q \mathbb {Q} for many hyperelliptic modular curves without a rational cusp in the L-functions and Modular Forms Database.
Fields of Study & Subjects
Iterative Methods for Nonlinear Equations
Advanced Numerical Analysis Techniques
History and Theory of Mathematics
Publication details
- Journal / source
- Contemporary mathematics - American Mathematical Society
- Pages
- 345–354
- Publication date
- 1 May 2026
- Language
- EN