Generating sequences and semigroups of valuations on 2 dimensional normal local rings
In this thesis we develop a method for constructing generating sequences for valuations dominating the ring of a two dimensional quotient singularity. Suppose that K is an algebraically closed field of characteristic zero, K[X, Y ] is a polynomial ring over K and ? is a rational rank 1 valuation of the field K(X, Y ) which dominates K[X, Y ](X,Y ) . Given a finite Abelian group H acting diagonally on K[X, Y ], and a generating sequence of ? in K[X, Y ] whose members are eigenfunctions for the action of H, we compute a generating sequence for the invariant ring K[X, Y ] H. We use this to compute the semigroup SK[X,Y ]H (?) of values of elements of K[X, Y ]H. We further determine when SK[X,Y ]H (?) is a finitely generated SK[X,Y ]H (?)-module.
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