English

On pairs of commuting derivations of the polynomial ring in two variables

Commutative Algebra 2009-11-12 v1 Rings and Algebras

Abstract

Let kk be an arbitrary field of characteristic zero, k[x,y]k[x, y] be the polynomial ring and DD a kk-derivation of the ring k[x,y]k[x, y]. Recall that a nonconstant polynomial Fk[x,y]F\in k[x, y] is said to be a Darboux polynomial of the derivation DD if D(F)=λFD(F)=\lambda F for some polynomial λk[x,y]\lambda \in k[x, y]. We prove that any two linearly independent over the field kk commuting kk-derivations D1D_{1} and D2D_{2} of the ring k[x,y]k[x, y] either have a common Darboux polynomial, or D1=Du1,D2=Du2D_{1}=D_{u_{1}}, D_{2}=D_{u_{2}} are Jacobian derivations i.e., Di(f)=detJ(ui,f)D_{i}(f)=\det J(u_{i}, f) for every fk[x,y],i=1,2,f\in k[x, y], i=1, 2, where the polynomials u1,u2u_{1}, u_{2} satisfy the condition detJ(u1,u2)=ck.\det J(u_{1}, u_{2})=c\in k^{\star}. This statement about derivations is an analogue of the known fact from Linear Algebra about common eigenvectors of pairs of commuting linear operators.

Keywords

Cite

@article{arxiv.0911.2073,
  title  = {On pairs of commuting derivations of the polynomial ring in two variables},
  author = {Anatoliy P. Petravchuk},
  journal= {arXiv preprint arXiv:0911.2073},
  year   = {2009}
}

Comments

5 pages