Extended affine root systems of type .
We analyze stability for switched systems which are composed of both continuous-time and discrete-time subsystems. By considering a Lie algebra generated by all subsystem matrices, we show that if all subsystems are Hurwitz/Schur stable and this Lie algebra is solvable, then there is a common quadratic Lyapunov function for all subsystems and thus the switched system is exponentially stable under arbitrary switching. When not all subsystems are stable and the same Lie algebra is solvable, we show...
Soient un anneau commutatif et une -algèbre associative quelconque. Nous calculons le groupe d’homologie de la -algèbre de Lie des matrices de “trace nulle” sur . Le groupe ainsi déterminé est un groupe d’homologie d’un complexe inspiré d’A. Connes; il est isomorphe à lorsque est commutative. Nous obtenons également des résultats pour un groupe d’homologie relative associé à une surjection de -algèbres. Les démonstrations utilisent la classification des extensions centrales et des...
We study (non-abelian) extensions of a given hom-Lie algebra and provide a geometrical interpretation of extensions, in particular, we characterize an extension of a hom-Lie algebra by another hom-Lie algebra and discuss the case where has no center. We also deal with the setting of covariant exterior derivatives, Chevalley derivative, Maurer-Cartan formula, curvature and the Bianchi identity for the possible extensions in differential geometry. Moreover, we find a cohomological obstruction...
Using extremal projectors, Zhelobenko solved extremal equations in a generic Verma module of a complex semi-simple Lie algebra. We will solve similar equations in the semi-classical case. Our proof will be geometric. In the appendix, we give a factorization for the extremal projector of the Virasoro algebra in the semi-classical case.
In recent papers, the Right and the Strong* topologies have been introduced and studied on general Banach spaces. We characterize different types of continuity for multilinear operators (joint, uniform, etc.) with respect to the above topologies. We also study the relations between them. Finally, in the last section, we relate the joint Strong*-to-norm continuity of a multilinear operator T defined on C*-algebras (respectively, JB*-triples) to C*-summability (respectively, JB*-triple-summability)....
Novikov algebras were introduced in connection with the Poisson brackets of hydrodynamic type and Hamiltonian operators in the formal variational calculus. Fermionic Novikov algebras correspond to a certain Hamiltonian superoperator in a supervariable. In this paper, we show that fermionic Novikov algebras equipped with invariant non-degenerate symmetric bilinear forms are Novikov algebras.