On Betti series of the universal modules of second order derivations of \frac{k[x1,x2,...,xs]}{(f)}

Let R be a coordinate ring of an affine irreducible curve represented by \frac{k[x1,x2,...,xs]}{(f)} and m be a maximal ideal of R. In this article, the Betti series of W2(Rm) is studied. We proved that the Betti series of W2(Rm), where W2(Rm) denotes the universal module of second order derivations of Rm, is a rational function under some conditions.Derivations and their universal modules have been studied by many mathematicians. Erdo˘gan [2] has studied when the Betti series of a universal module of second order derivations is a rational function. In this work, theanalogue of this question for the Betti series of Ω2(Rm), where R = k[x1,x2,...,xs] (f) and m is a maximal ideal of R, has been studied. At the end, we give an example to illustrate our result. All rings we will study in this work will be commutative with identity. Now, we recall some important properties.

On Betti series of the universal modules of second order derivations of k[x1,x2,...,xs] (f)

Let R be a coordinate ring of an affine irreducible curve represented by \frac{k[x1,x2,...,xs]}{(f)} and m be a maximal ideal of R. In this article, the Betti series of W2(Rm) is studied. We proved that the Betti series of W2(Rm), where W2(Rm) denotes the universal module of second order derivations of Rm, is a rational function under some conditions.Derivations and their universal modules have been studied by many mathematicians. Erdo˘gan [2] has studied when the Betti series of a universal module of second order derivations is a rational function. In this work, theanalogue of this question for the Betti series of Ω2(Rm), where R = k[x1,x2,...,xs] (f) and m is a maximal ideal of R, has been studied. At the end, we give an example to illustrate our result. All rings we will study in this work will be commutative with identity. Now, we recall some important properties.

___

  • C ¸ imen, N., Erdo˘ gan, A.: Projective dimension of the universal modules for the product of a hypersurface and affine t-space. Comm. Algebra 27(10), 4737–4741 (1999).
  • Erdo˘ gan, A.: Results on Betti series of the universal modules of the second order derivation. Hacet.J.Math. Stat. 40(3), 449–452 (2011).
  • Erdo˘ gan, A.: Homological dimension of the universal modules for hypersurfaces. Comm. Algebra 24(5), 1565–1573 (1996).
  • Kunz, E.: Introduction to Commutative Algebra and Algebraic Geometry. Boston: Birkhauser 1985. Nakai, Y.: High order derivations 1. Osaka J.Math. 7, 1–27 (1970).