1998/09/08 by Everett W. Howe, Franck Leprevost, Bjorn Poonen · 1 citation
Mathematics · #math.NT
published as Forum Math. 12, no. 3 (2000), 315--364
arxiv created 1998/09/08 · arxiv updated 2009/12/01
We construct examples of families of curves of genus 2 or 3 over Q whose Jacobians split completely and have various large rational torsion subgroups. For example, the rational points on a certain elliptic surface over P1 of positive rank parameterize a family of genus-2 curves over Q whose Jacobians each have 128 rational torsion points. Also, we find the genus-3 curve 15625(X4 + Y4 + Z4) - 96914(X2 Y2 + X2 Z2 + Y2 Z2) = 0, whose Jacobian has 864 rational torsion points. This paper has appeared in Forum Math. 12 (2000) 315-364.