English

The multivariate Serre conjecture ring

Commutative Algebra 2022-07-05 v1

Abstract

It is well-known that for any commutative unitary ring R\mathbf{R}, the Serre conjecture ring RX\mathbf{R}\langle X \rangle, i.e., the localization of the univariate polynomial ring R[X]\mathbf{R}[X] at monic polynomials, is a B\'ezout domain of Krull dimension 1\leq 1 if so is R\mathbf{R}. Consequently, defining by induction RX1,,Xn:=(RX1,,Xn1)Xn\mathbf{R}\langle X_1,\ldots,X_n \rangle:=(\mathbf{R}\langle X_1,\ldots,X_{n-1}\rangle)\langle X_n\rangle, the ring RX1,,Xn\mathbf{R}\langle X_1,\ldots,X_n \rangle is a B\'ezout domain of Krull dimension 1\leq 1 if so is R\mathbf{R}. The fact that RX1,,Xn\mathbf{R}\langle X_1,\ldots,X_n \rangle is a B\'ezout domain when R\mathbf{R} is a valuation domain of Krull dimension 1\leq 1 was the cornerstone of Brewer and Costa's theorem stating that if R\mathbf{R} is a one-dimensional arithmetical ring then finitely generated projective R[X1,,Xn]\mathbf{R}[X_1,\dots,X_n]-modules are extended. It is also the key of the proof of the Gr\"obner Ring Conjecture in the lexicographic order case, namely the fact that for any valuation domain R\mathbf{R} of Krull dimension 1\leq 1, any nN>0n \in \mathbb{N}_{>0}, and any finitely generated ideal II of R[X1,,Xn]\mathbf{R}[X_1, \dots, X_n], the ideal LT(I)\operatorname{LT}(I) generated by the leading terms of the elements of II with respect to the lexicographic monomial order is finitely generated. Since the ring RX1,,Xn\mathbf{R}\langle X_1,\ldots,X_n\rangle can also be defined directly as the localization of the multivariate polynomial ring R[X1,,Xn]\mathbf{R}[X_1,\dots,X_n] at polynomials whose leading coefficients according to the lexicographic monomial order with X1<X2<<XnX_1<X_2<\cdots<X_n is 11, we propose to generalize the fact that RX1,,Xn\mathbf{R}\langle X_1,\ldots,X_n\rangle is a B\'ezout domain of Krull dimension 1\leq 1 if so is R\mathbf{R} to any rational monomial order, bolstering the evidence for the Gr\"obner Ring Conjecture in the rational case.

Keywords

Cite

@article{arxiv.2207.01034,
  title  = {The multivariate Serre conjecture ring},
  author = {Luc Guyot and Ihsen Yengui},
  journal= {arXiv preprint arXiv:2207.01034},
  year   = {2022}
}

Comments

12 pages, no figure