Variational problems for riemannian functionals and arithmetic groups
p. 5-62
Counting p-groups and nilpotent groups
p. 63-112
Groups acting on trees : from local to global structure
p. 113-150
Lattices in product of trees
p. 151-194
Erratum to : Morphisms, line bundles and moduli spaces in real algebraic geometry
p. 195