(Note change of room.) TECHNION DEPARTMENT OF MATHEMATICS ALGEBRA SEMINAR SPEAKER: Yuval Ginosar, Haifa University TITLE: Semi-invariant matrices. DATE: Thursday, March 22, 2012 TIME: 13:30 PLACE: Amado 814 (Note change of room.) ABSTRACT: The semi-invariants of a module-algebra over a group $G$ are the elements in its 1-dimensional constituents. These elements span a subalgebra, called thesemi-center, which is graded by the linear characters of $G$. By studying the projective representations of $G$, we describe the semi-center of matrix algebras, or more generally of artinian semi-simple $G$-module-algebras. A joint work with O. Schnabel. --------------------------------------------------------- Technion Math. Net (TECHMATH) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: Eli Aljadeff <elialjadeff@gmail.com>