Curve equations from expansions of 1-forms at a nonrational point

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Authors: Raymond van Bommel, Edgar Costa, Bjorn Poonen, Padmavathi Srinivasan
Cited by: 0

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