La semi-caractéristique d’Euler-Poincaré des faisceaux -quadratiques sur un schéma de Cohen-Macaulay
To every morphism of differential graded Lie algebras we associate a functors of artin rings whose tangent and obstruction spaces are respectively the first and second cohomology group of the suspension of the mapping cone of . Such construction applies to Hilbert and Brill-Noether functors and allow to prove with ease that every higher obstruction to deforming a smooth submanifold of a Kähler manifold is annihilated by the semiregularity map.