Divisorial linear algebra over normal affine semigroup ringsAlgebra & Discrete Mathematics
|Speaker:||Winfried Bruns, Universitat Osnabrueck Germany|
|Start time:||Fri, Feb 28 2003, 12:10PM|
In joint work with J. Gubeladze we have explored the ``linear algebra'' properties of divisorial ideals over normal semigroup rings. In invariant theory these ideals appear as modules of semi-invariants of the actions of algebraic tori. The properties and invariants to be discussed are, among other things, the Cohen-Macaulayness and the number of generators. In particular we show that there exist, up to isomorphism, only finitely many Cohen-Macaulay (divisorial) ideals.