Results on the Ratliff–Rush Closure and the Integral Closedness of Powers of Certain Monomial Curves

Abstract

Starting from [1] we compute the Groebner basis for the defining ideal, P, of the monomial curves that correspond to arithmetic sequences, and then give an elegant description of the generators of powers of the initial ideal of P, inP. The first result of this article introduces a procedure for generating infinite families of Ratliff–Rush ideals, in polynomial rings with multivariables, from a Ratliff–Rush ideal in polynomial rings with two variables. The second result is to prove that all powers of inP are Ratliff–Rush. The proof is through applying the first result of this article combined with Corollary 12 in [2]. This generalizes the work of [4] (or [5])\ for the case of arithmetic sequences. Finally, we apply the main result of [3] to give the necessary and sufficient conditions for the integral closedness of any power of inP.

Key Words:

• Integral closure
• Monomial curves
• Monomial ideals
• Normal ideals
• Ratliff–Rush closure

2000 Mathematics Subject Classification:

• 13P10

Notes

Communicated by R. Wiegard.