Homology of Gaussian groups

We describe new combinatorial methods for constructing explicit free resolutions of Z by ZG-modules when G is a group of fractions of a monoid where enough lest common multiples exist ("locally Gaussian monoid"), and therefore, for computing the homology of G. Our constructions apply in particular to all Artin-Tits groups of finite Coexter type. Technically, the proofs rely on the properties of least common multiples in a monoid.