Block-diagonal reduction of matrices over an <Emphasis Type="Italic">n</Emphasis>-simple Bézout domain (n ≥ 3)

It is known that a simple Bézout domain is the domain of elementary divisors if and only if it is 2-simple. The block-diagonal reduction of matrices over an n -simple Bézout domain (n ≥ 3) is realized.     

2-Simple ore domains of stable rank 1

It is known that a simple Bézout domain is a domain of elementary divisors if and only if it is 2-simple. We prove that, over a 2-simple Ore domain of stable rank 1, an arbitrary matrix that is not a divisor of zero is equivalent to a canonical diagonal matrix.     

On the Simultaneous Basis Property in Prüfer Domains

In this paper we prove that if D is a Prüfer domain such that given a proper invertible integral ideal A of D there exists a nonempty finite set of finitely generated maximal ideals that contain A, then D has the simultaneous basis property. This result is used to study two old open problems: "Does every Prüfer domain have the PA-property?", and "Is every Bézout domain an elementary divisor domain?". We include also a new different proof of the simultaneous basis property for valuations domains.     

Decidability of the theory of modules over Prüfer domains with dense value groups

We provide algebraic conditions ensuring the decidability of the theory of modules over effectively given Prüfer (in particular Bézout) domains whose localizations at maximal ideals have dense value groups. For Bézout domains, these conditions are also necessary.     

Finitely Presented Modules Over Semihereditary Rings

We prove that each almost local-global semihereditary ring R has the stacked bases property and is almost Bézout. More precisely, if M is a finitely presented module, its torsion part tM is a direct sum of cyclic modules where the family of annihilators is an ascending chain of invertible ideals. These ideals are invariants of M. Moreover, M/tM is a projective module which is isomorphic to a direct sum of finitely generated ideals. These ideals allow us to define a finitely generated ideal whose isomorphism class is an invariant of M. The idempotents and the positive integers defined by the rank of M/tM are invariants of M too. It follows that each semihereditary ring of Krull-dimension one or of finite character, in particular each hereditary ring, has the stacked base property. These results were already proved for Prüfer domains by Brewer, Katz, Klinger, Levy, and Ullery. It is also shown that every semihereditary Bézout ring of countable character is an elementary divisor ring.     

Right Bézout ring with waist is a right Hermite ring

We study noncommutative rings in which the Jacobson radical contains a completely prime ideal. It is proved that a right Bézout ring in which the Jacobson radical contains a completely prime ideal is a right Hermite ring. We describe a new class of Bézout rings that are not elementary divisor rings.     

PURE-INJECTIVE MODULES NEED NOT BE RD-INJECTIVE

Abstract

It is shown that if R is a GCD domain which is not Bézout, then there exist pure-injective R-modules which are not RD-injective.     

A generalization of the Jaffard–Ohm–Kaplansky Theorem

The well-known Jaffard–Ohm–Kaplansky Theorem states that every abelian ?-group can be realized as the group of divisibility of a commutative Bézout domain. To date there is no realization (except in certain circumstances) of an arbitrary, not necessarily abelian, ?-group as the group of divisibility of an integral domain. We show that using filters on lattices we can construct a nice quantal frame whose “group of divisibility” is the given ?-group. We then show that our construction when applied to an abelian ?-group gives rise to the lattice of ideals of any Prüfer domain assured by the Jaffard–Ohm–Kaplansky Theorem. Thus, we are assured of the appropriate generalization of the Jaffard–Ohm–Kaplansky Theorem.     

A short proof of Cartan’s Nullstellensatz for entire functions in $${\mathbb{C}^n}$$

Using the fact that the maximal ideals in the polydisk algebra are given by the kernels of point evaluations, we derive a simple formula that gives a solution to the Bézout equation in the space of all entire functions of several complex variables. Thus a short and easy analytic proof of Cartan’s Nullstellensatz is obtained.     

Radically perfect prime ideals in polynomial rings

We call an ideal I of a commutative ring R radically perfect if among the ideals of R whose radical is equal to the radical of I the one with the least number of generators has this number of generators equal to the height of I. Let R be a Noetherian integral domain of Krull dimension one containing a field of characteristic zero. Then each prime ideal of the polynomial ring R[X] is radically perfect if and only if R is a Dedekind domain with torsion ideal class group. We also show that over a finite dimensional Bézout domain R, the polynomial ring R[X] has the property that each prime ideal of it is radically perfect if and only if R is of dimension one and each prime ideal of R is the radical of a principal ideal.     

A Mordell-Lang plus Bogomolov type result for curves in \mathbbGm2{\mathbb{G}_{m}^{2}}

We prove a sharper so-called Mordell-Lang plus Bogomolov type result for curves lying in the two-dimensional linear torus. We mainly follow the approach of Rémond in (Comp Math 134:337–366, 2002), using Vojta and Mumford type inequalities. In the special case we consider, we improve Rémond’s main result using a better Bogomolov property and an elementary arithmetic Bézout theorem.     

Semiperfect ipri-rings and right Bézout rings

We present a survey of some results on ipri-rings and right Bézout rings. All these rings are generalizations of principal ideal rings. From the general point of view, decomposition theorems are proved for semiperfect ipri-rings and right Bézout rings.     

A Mordell-Lang plus Bogomolov type result for curves in $${\mathbb{G}_{m}^{2}}$$

We prove a sharper so-called Mordell-Lang plus Bogomolov type result for curves lying in the two-dimensional linear torus. We mainly follow the approach of Rémond in (Comp Math 134:337–366, 2002), using Vojta and Mumford type inequalities. In the special case we consider, we improve Rémond’s main result using a better Bogomolov property and an elementary arithmetic Bézout theorem.      

Elementary matrix reduction over certain rings

We explore elementary matrix reduction over certain rings characterized by properties related to stable range. Let R be a commutative ring. We call R locally stable if aR+bR = R??x∈R such that R∕(a+bx)R has stable range 1. We study locally stable rings and prove that every locally stable Bézout ring is an elementary divisor ring. Many known results on domains are thereby generalized.     

Flatness of boundary coupled second order partial differential equations

We sketch algebraic and trajectory related controllability results for systems described by boundary coupled partial differential equations of second order in one spatial dimension. Those systems may be described by modules over a Bézout domain ℛ_ℚ generated by particular Mikusinski–Operators with compact support. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Rings with linearly ordered right annihilators

We introduce the class of lineal rings, defined by the property that the lattice of right annihilators is linearly ordered. We obtain results on the structure of these rings, their ideals, and important radicals; for instance, we show that the lower and upper nilradicals of these rings coincide. We also obtain an affirmative answer to the Köthe Conjecture for this class of rings. We study the relationships between lineal rings, distributive rings, Bézout rings, strongly prime rings, and Armendariz rings. In particular, we show that lineal rings need not be Armendariz, but they fall not far short.     

On the classification of exceptional planar functions over \mathbb {F}_{p}

We will present many strong partial results towards a classification of exceptional planar/PN monomial functions on finite fields. The techniques we use are the Weil bound, Bézout’s theorem, and Bertini’s theorem.     

Controllability of distributed parameter systems: Illustrative examples for an algebraic approach.

Boundary coupled partial differential equations of second order are seen as convolutional systems over a Bézout domain RQ of particular distributions and ultradistributions with compact support. For two simple examples this property of RQ is employed in order two find a flat output, i.e., a variable that allows the parametrization of the system trajectories in an appropriate solution space. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Some remarks on almost l-groups

The divisibility group of every Bézout domain is an abelian l-group. Conversely, Jaffard, Kaplansky, and Ohm proved that each abelian l-group can be obtained in this way, which generalizes Krull’s theorem for abelian linearly ordered groups. Dumitrescu, Lequain, Mott, and Zafrullah [3] proved that an integral domain is almost GCD if and only if its divisibility group is an almost l-group. Then they asked whether the Krull-Jaffard-Kaplansky-Ohm theorem on l-groups can be extended to the framework of almost l-groups, and asked under what conditions an almost l-group is lattice-ordered [3, Questions 1 and 2]. This note answers the two questions. Received: 29 April 2008     

Flatness-based control without prediction: example of a vibrating string

Stable trajectory tracking by boundary control is discussed for a string with a mass at its free end. Based on the known fact that the ring of operators used to describe the system is a Bézout ring it is shown that predictions are not required for stabilization if distributed delays are admitted. The method is rather general for systems of boundary coupled wave equations with boundary control that can be modeled as delay systems with commensurate delays. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)