School of Mathematics and Statistics
Number Theory Seminar 

At the beginning of this talk I will basically finish the talk from last week with the classification theorem for endomorphism algebras of abelian varieties and some examples to make everything a bit clearer. Then I will introduce CMtypes on abelian varieties. One can show that for every CMtype there exists an ablian variety (over the complex numbers) of this CMtype, which is, however, not necessarily simple. Therefore, I will give a grouptheoretic characterization of CMtypes which will help us later to decide whether a CMtype is primitive (i.e. the corresponding abelian variety is simple) or not. 