Algèbres d'opérateurs différentiels et quotients des algèbres enveloppantes
On présente une définition et une construction unifée des homologies et cohomologies d’algèbres et de modules sur ces algèbres et de modules sur ces algèbres dans le cas d’algèbres associatives ou commutatives ou de Lie ou de Gertsenhaber. On sépare la construction linéaire des cogèbres ou bicogèbres qui traduisent les symétries des relations de définition de la structure de la partie structure qui apparaît ici comme une codérivation de degré 1 et de carré nul de la cogèbre ou de la bicogèbre.
Lax operator algebras constitute a new class of infinite dimensional Lie algebras of geometric origin. More precisely, they are algebras of matrices whose entries are meromorphic functions on a compact Riemann surface. They generalize classical current algebras and current algebras of Krichever-Novikov type. Lax operators for 𝔤𝔩(n), with the spectral parameter on a Riemann surface, were introduced by Krichever. In joint works of Krichever and Sheinman their algebraic structure was revealed and...
In this paper, we present an abstract framework which describes algebraically the derivation of order conditions independently of the nature of differential equations considered or the type of integrators used to solve them. Our structure includes a Hopf algebra of functions, whose properties are used to answer several questions of prime interest in numerical analysis. In particular, we show that, under some mild assumptions, there exist integrators of arbitrarily high orders for arbitrary (modified)...