On the algebra of constants of polynomial derivations in two variables
Volume 83 / 2000
Colloquium Mathematicum 83 (2000), 267-269
DOI: 10.4064/cm-83-2-267-269
Abstract
Let d be a k-derivation of k[x,y], where k is a field of characteristic zero. Denote by $\widetilde d$ the unique extension of d to k(x,y). We prove that if ker d ≠ k, then ker $\widetilde d$ = (ker d)_0, where (ker d)_0 is the field of fractions of ker d.
