Computing isogenies from modular equations between Jacobians of genus 2 curves
Computing isogenies from modular equations between Jacobians of genus 2 curves
Let k be a field of large enough characteristic. We present an algorithm solving the following problem: given two genus 2 curves over k with isogenous Jacobians, compute an isogeny between them explicitly. This isogeny can be either an {\ell}-isogeny or, in the real multiplication case, an isogeny with cyclic …