Sommaire du Fascicule no. 1

Around the Littlewood conjecture in Diophantine approximation
p. 5-18
Arithmetic Properties of Generalized Rikuna Polynomials
p. 19-33
Un théorème de zéros dans les groupes algébriques commutatifs
p. 35-44
Weight reduction for cohomological mod p modular forms over imaginary quadratic fields
p. 45-71
On computing Belyi maps
p. 73-131

Sommaire du Fascicule no. 2

Denominators of Igusa class polynomials
p. 5-29
Sur le rang des variétés abéliennes sur un corps de fonctions
p. 31-46
Heights and regulators of number fields and elliptic curves
p. 47-62
Ranks of quadratic twists of elliptic curves
p. 63-98