Ga-actions on affine T-varieties
Alvaro Liendo (Chile / Grenoble)
9.11.2009, 16:15 Uhr
Institut fuer Mathematik
Arnimallee 3, Rm. 119
Let X = spec A be a normal affine variety endowed with an effective action of a torus T of dimension n. To introduce a Ga-action on X is equivalent to fix a locally nilpotent derivation D on the Zn-graded algebra A. In this talk we show some classification result of pairs (A,D) in the case where D is homogeneous and with special emphasis in the case where the general orbits of the Ga-action are contained in the orbit closures of the T-action. In particular, we give the birational characterization of normal affine varieties with trivial Makar-Limanov invariant.