Given a valuation on the function field k( x; y), we examine the set of images of nonzero elements of the underlying polynomial ring k[ x; y] under this valuation. For an arbitrary field k, a Noetherian power series is a map z : Q --> k that has Noetherian (i.e., reverse well-ordered) support. Each Noetherian power series induces a natural valuation on k( x; y). Although the value groups corresponding to such valuations are well-understood, the restrictions of the valuations to underlying polynomial rings have yet to be characterized. Let Lambda(n) denote the images under the valuation v of all nonzero polynomials f is an element of k[ x; y] of at most degree n in the variable y. We construct a bound for the growth of Lambda(n) with respect to n for arbitrary valuations, and then specialize to valuations that arise from Noetherian power series. We provide a sufficient condition for this bound to be tight.
First published in Proceedings of the American Mathematical Society in 2004, published by the American Mathematical Society
Mosteig, E., Sweedler, M. The Growth of Valuations on Rational Function Fields in Two Variables, Proceedings of the American Mathematical Society. vol. 132 (2004) pp. 3473-3483.