Dérivations et hautes dérivations dans certains corps gauches de séries de Laurent

Let k be a field of characteristic zero, F=k((Y)) the local field of Laurent series in a variable Y, and ∂ Y the usual derivation of F. The purpose of this paper is the complete description of k-derivations on the formal pseudo-differential operator skewfield K=F(XX, ∂ Y )). An application of this result is given to study the structure of higher derivations in skewfields of characteristic zero