Journal of the
Korean Mathematical Society JKMS

Let $F^\alpha G$ be a twisted group algebra. A subalgebra of $F^\alpha G$ generated by all class sums of partition ${\mathcal P}$ of $G$ is called a projective class algebra in $F^\alpha G$ associated with partition ${\mathcal P}$. In this paper we study various partitions of $G$ determined by actions of certain operator groups on $G$ and construct projective class algebras depending on the actions. With regard to projective class algebras, we investigate structures of associated skew group algebras and fixed group algebras.

Keywords: group algebra, class algebra, projective subclass algebra

MSC numbers: Primary 16H05, 16W22