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S. Kabbaj

Publications and source records attributed to S. Kabbaj.

32 records · Page 2Linked to original sources
arXiv2009

On the prime ideal structure of symbolic Rees algebras

This paper contributes to the study of the prime spectrum and dimension theory of symbolic Rees algebra over Noetherian domains. We first establish some general results on the prime ideal structure of subalgebras of affine domains, which actually arise, in the Noetherian context, as domains between a domain $A$ and $A[a^{-1}]$. We then examine closely the special context of symbolic Rees algebras (which yielded the first counter-example to the Zariski-Hilbert problem). One of the results states that if $A$ is a Noetherian domain and $p$ a maximal ideal of $A$, then the Rees algebra of $p$ inherits the Noetherian-like behavior of being a stably strong S-domain. We also investigate graded rings associated with symbolic Rees algebras of prime ideals $p$ such that $A_{p}$ is a rank-one DVR and close with an application related to Hochster's result on the coincidence of the ordinary and symbolic powers of a prime ideal.

math.AC↗
arXiv2008

Constituent Groups of Clifford Semigroups Arising from t-Closure

The t-class semigroup of an integral domain R, denoted S_t(R), is the semigroup of fractional t-ideals modulo its subsemigroup of nonzero principal ideals with the operation induced by ideal t-multiplication. We recently proved that if R is a Krull-type domain, then S_t(R) is a Clifford semigroup. This paper aims to describe the idempotents of S_t(R) and the structure of their associated groups. We extend and recover well-known results on class semigroups of valuation domains and Prufer domains of finite character.

math.AC↗
arXiv2008

Bouvier's conjecture

This paper deals with Bouvier's conjecture which sustains that finite-dimensional non-Noetherian Krull domains need not be Jaffard

math.AC↗
arXiv2008

t-Class semigroups of Noetherian domains

The t-class semigroup of an integral domain is the semigroup of fractional t-ideals modulo its subsemigroup of nonzero principal ideals with the operation induced by ideal t-multiplication. This paper investigates ring-theoretic properties of a Noetherian domain that reflect reciprocally in the Clifford or Boolean property of its t-class semigroup.

math.AC↗
arXiv2008

Trivial extensions defined by Prufer conditions

This paper deals with well-known extensions of the Prufer domain concept to arbitrary commutative rings. We investigate the transfer of these notions in trivial ring extensions (also called idealizations) of commutative rings by modules and then generate original families of rings with zerodivisors subject to various Prufer conditions. The new examples give further evidence for the validity of Bazzoni-Glaz conjecture on the weak dimension of Gaussian rings. Moreover, trivial ring extensions allow us to widen the scope of validity of Kaplansky-Tsang conjecture on the content ideal of Gaussian polynomials.

math.AC↗
arXiv2007

t-Class Semigroups of Integral Domains

The t-class semigroup of an integral domain is the semigroup of the isomorphy classes of the t-ideals with the operation induced by ideal t-multiplication. This paper investigates ring-theoretic properties of an integral domain that reflect reciprocally in the Clifford or Boolean property of its t-class semigroup. Contexts (including Lipman and Sally-Vasconcelos stability) that suit best t-multiplication are studied in an attempt to generalize well-known developments on class semigroups. We prove that a Prufer v-multiplication domain (PVMD) is of Krull type (in the sense of Griffin) if and only if its t-class semigroup is Clifford. This extends Bazzoni and Salce's results on valuation domains and Prufer domains. We also characterize GCD domains with Boolean t-class semigroup, recovering thus recent results on Bezout domains.

math.AC↗
arXiv2006

On the Dimension Theory of Polynomial Rings over Pullbacks

This review paper deals with dimension theory of polynomial rings over certain families of pullbacks. While the literature is plentiful, this field is still developing and many contexts are yet to be explored. I will thus restrict the scope of the present survey, mainly, to topics I have worked on over the last decade. The set of pullback constructions studied includes D+M, D+(X_{1}, >..., X_{n})D_{S}[X_{1}, ..., X_{n}], A+XB[X], and D+I.

math.AC↗
arXiv2006

On the Prime Ideal Structure of Tensor Products of Algebras

This paper is concerned with the prime spectrum of a tensor product of algebras over a field. It seeks necessary and sufficient conditions for such a tensor product to have the S-property, strong S-property, and catenarity. Its main results lead to new examples of stably strong S-rings and universally catenarian rings. The work begins by investigating the minimal prime ideal structure. Throughout, several results on polynomial rings are recovered, and numerous examples are provided to illustrate the scope and sharpness of the results.

math.AC↗
arXiv2006

Class Semigroups of Integral Domains

This paper seeks ring-theoretic conditions of an integral domain R that reflect in the Clifford property or Boolean property of its class semigroup S(R), that is, the semigroup of the isomorphy classes of the nonzero (integral) ideals of R with the operation induced by multiplication. Precisely, in Section 3, we characterize integrally closed domains with Boolean class semigoup; in this case, S(R) identifies with the Boolean semigroup formed of all fractional overrings of R. In Section 4, we investigate Noetherian-like settings where the Clifford and Boolean properties of S(R) coincide with (Lipman and Sally-Vasconcelos) stability conditions; a main feature is that the Clifford property forces t-locally Noetherian domains to be one-dimensional Noetherian domains. Section 5 studies the transfer of the Clifford and Boolean properties to various pullback constructions. Our results lead to new families of integral domains with Clifford or Boolean class semigroup, moving therefore beyond the contexts of integrally closed domains or Noetherian domains.

math.AC↗
arXiv2006

Tensor Products of Cohen-Macaulay Rings. Solution to a Problem of Grothendieck

In this paper we solve a problem, originally raised by Grothendieck, on the transfer of Cohen-Macaulayness to tensor products of algebras over a field. As a prelude to this, we investigate the grade for some specific types of ideals that play a primordial role within the ideal structure of such constructions.

math.AC↗
arXiv2006

On The Class Group of a Graded Domain

This paper studies the class group of graded integral domains. As an application, we state a decomposition theorem for class groups of semigroup rings. This recovers well-known results developed for the classic contexts of polynomial rings and Krull semigroup rings. Our results are backed by original examples.

math.AC↗
arXiv2006

Trivial Extensions of Local Rings and a Conjecture of Costa

This paper partly settles a conjecture of Costa on (n,d)-rings, i.e., rings in which n-presented modules have projective dimension at most d. For this purpose, a theorem studies the transfer of the (n,d)-property to trivial extensions of local rings by their residue fields. It concludes with a brief discussion -backed by original examples- of the scopes and limits of our results.

math.AC↗
arXiv2006

Trivial Extensions Defined by Coherent-like Conditions

This paper investigates coherent-like conditions and related properties that a trivial extension might inherit from the ground ring over some classes of modules. It captures previous results dealing primarily with coherence, and also establishes satisfactory analogues of well-known coherence-like results on pullback constructions. Our results generate new families of examples of rings (with zerodivisors) subject to a given coherent-like condition.

math.AC↗