activity
20182025
most citedSign choices in the AGM for genus two theta constants

5 citations · 13 across the 13 of their papers we have counts for

collaborators

14 papers

math.NT2025

Fast evaluation of Riemann theta functions in any dimension

Noam D. Elkies, Jean Kieffer

We describe an algorithm to numerically evaluate Riemann theta functions in any dimension in quasi-linear time in terms of the required precision, uniformly on reduced input. This…

math.NT2024

The asymptotic distribution of Elkies primes for reductions of abelian varieties is Gaussian

Alexandre Benoist, Jean Kieffer

We generalize the notion of Elkies primes for elliptic curves to the setting of abelian varieties with real multiplication (RM), and prove the following. Let be an abelian vari…

math.NT2024

Spanning isogeny classes of principally polarized abelian surfaces with RM

Jean Kieffer

We describe how isogenies between principally polarized abelian surfaces (PPAS) with real multiplication (RM) can be decomposed into elementary isogeny types. This leads to a strat…

math.AG2023

A database of basic numerical invariants of Hilbert modular surfaces

Eran Assaf, Angelica Babei, Ben Breen +8

We describe algorithms for computing geometric invariants for Hilbert modular surfaces, and we report on their implementation.

math.NT2023

Computing isogeny classes of typical principally polarized abelian surfaces over the rationals

Raymond van Bommel, Shiva Chidambaram, Edgar Costa +1

We describe an efficient algorithm which, given a principally polarized (p.p.) abelian surface over with geometric endomorphism ring equal to , compute…

math.NT2022★ 1 cited

Counting points on abelian surfaces over finite fields with Elkies's method

Jean Kieffer

We generalize Elkies's method, an essential ingredient in the SEA algorithm to count points on elliptic curves over finite fields of large characteristic, to the setting of p.p. ab…

math.NA2022

Certified Newton schemes for the evaluation of low-genus theta functions

Jean Kieffer

Theta functions and theta constants in low genus, especially genus 1 and 2, can be evaluated at any given point in quasi-linear time in the required precision using Newton schemes…

math.NT2021★ 1 cited

Upper bounds on the heights of polynomials and rational fractions from their values

Jean Kieffer

Let be a univariate polynomial or rational fraction of degree defined over a number field. We give bounds from above on the absolute logarithmic Weil height of in terms…

math.NT2020

Evaluating modular equations for abelian surfaces

Jean Kieffer

We design efficient algorithms to evaluate modular equations of Siegel and Hilbert type for abelian surfaces over number fields or finite fields using complex approximations. Their…

math.NT2020★ 5 cited

Sign choices in the AGM for genus two theta constants

Jean Kieffer

Existing algorithms to compute genus 2 theta constants in quasi-linear time use Borchardt sequences, an analogue of the arithmetic-geometric mean for four complex numbers. In this…

math.AG2020★ 4 cited

Degree and height estimates for modular equations on PEL Shimura varieties

Jean Kieffer

We define modular equations in the setting of PEL Shimura varieties as equations describing Hecke correspondences, and prove upper bounds on their degrees and heights. This extends…

math.AG2020★ 2 cited

Computing isogenies from modular equations in genus two

Jean Kieffer, Aurel Page, Damien Robert

We present an algorithm solving the following problem: given two genus 2 curves over a field k with isogenous Jacobians, compute such an isogeny explicitly. This isogeny can be eit…

cs.CR2018

Towards practical key exchange from ordinary isogeny graphs

Luca De Feo, Jean Kieffer, Benjamin Smith

We revisit the ordinary isogeny-graph based cryptosystems of Couveignes and Rostovtsev-Stolbunov, long dismissed as impractical. We give algorithmic improvements that accelerate ke…

math.NT2018

Accelerating the Couveignes Rostovtsev Stolbunov key exchange protocol

Jean Kieffer

We study a key exchange protocol based on isogenies between ordinary elliptic curves over a finite field, first mentioned by Couveignes and investigated by Rostovtsev and Stolbunov…