Graded modules over G-sets II.
This paper deals with the notion of Gröbner δ-base for some rings of linear differential operators by adapting the works of W. Trinks, A. Assi, M. Insa and F. Pauer. We compare this notion with the one of Gröbner base for such rings. As an application we give some results on finiteness and on flatness of finitely generated left modules over these rings.
Let be a group algebra, and its quantum double. We first prove that the structure of the Grothendieck ring of can be induced from the Grothendieck ring of centralizers of representatives of conjugate classes of . As a special case, we then give an application to the group algebra , where is a field of characteristic and is a dihedral group of order .
We give a full description of locally finite -groups such that the normalized group of units of the group algebra over a field of characteristic has exponent .
Given a field K of characteristic p > 2 and a finite group G, necessary and sufficient conditions for the unit group U(KG) of the group algebra KG to be centrally metabelian are obtained. It is observed that U(KG) is centrally metabelian if and only if KG is Lie centrally metabelian.
Let U(RG) be the unit group of the group ring RG. Groups G such that U(RG) is FC-nilpotent are determined, where R is the ring of integers Z or a field K of characteristic zero.
Les « groupes totaux » sont les groupes pour lesquels la dimension du centre l’algèbre des invariants d’une algèbre simple centrale associée à un -cocycle sous l’action d’un relevé de l’action galoisienne à est constante quels que soient et . Dans cet article, nous montrons que les groupes quasi-CC (qui sont les groupes de centre cyclique et dont les centralisateurs des éléments hors du centre sont cycliques) sont totaux. Les groupes de type CC qui sont les groupes quasi-CC à centre trivial...