Le Matematiche  

A. Cherubini, Alberto Conte, Livio Porcu

Presentazione.

Livio Porcu

A remembrance of Umberto Gasapina.

Elisabetta Allevi

In this paper we introduce in the semigroup S, whose elements are to be evalued in terms of preference in a particular situation, a pre-order defined through semigroups of S. Then this pre-order is a preference relation with transitive indifference, which... see more

Edoardo Ballico

Here we study the topology of the dependency locus of sections of semiample vector bundles on complex projective varieties. The main motivation came from the study of subvarieties of the Grassmannians.

Renato Betti

Categories internal to an elementary topos are regarded as monads in the bicategory of spans of the topos and the main features of the theory are developed: functors, adjointness, module calculus, internal presheaves, internal completeness and cocompleten... see more

Mariagrazia Bianchi, Anna Gillio Berta Mauri, Libero Verardi

We characterize finite groups satisfying the following property: if x,y are two elements with the same p-power, then they permute.

Celestina Bonzini, Alessandra Cherubini

Semigroups, ideal extensions of a right (left)-zero semigroup by completely simple semigroup with zero adjoint, whose congruences are pairwise permutable are completely determined.

Celestina Cotti Ferrero, Giovanni Ferrero

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Paolo Duilio

In the paper we investigate through some examples the class of measurability, in Stoka's integral geometry theory, of weak subfamilies of a family of varieties, when we think of these from an intrinsic point of view. Then we suggest a new classification f... see more

Jolanda Laura Galbiati

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Silvia Imposimato

The family of systems of quadric cone and straith line, in A_3, proves to be measurable.

Antonio Lanteri

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Federico G. Lastaria

We give an explicit proof of the fundamental theorem of Grothendieck Galois theory: the category of separable algebras over a field K is anti-equivalent to the category of continuous actions on finite sets of the profinite fundamental group of K.

Cesarina Marchionna Tibiletti

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Franco Migliorini, Jenö Szép

This paper is a survey of a few previous works of the authors with other new results. We introduce a special decomposition of a finite group [semigroup] and determine its main properties. From such a decomposition one can construct, for a special class of... see more

Fiorenza Morini

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Brunetto Piochi

In this note quasi-abelian semigroups are studied and it is proved that they form an e-variety of orthodox semigroups. More, quasi-abelian regular Bruck-Reilly monoids are characterized as extensions of monoids which are (reverse) semidirect products of a... see more

Giuseppe Pirillo

Recently it has been proved that a finitely generated semigroup having the ?-iteration property is finite. Here we prove that, under certain conditions, the hypothesis that the generators are finitely many can be omitted. As the added conditions are alway... see more

Vladimir Repnitskii

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Giulio Santoro

The family of systems of parabolic cylinder, point and plane in A_3, proves to be measurable.

Boris M. Schein

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Ada Varisco

We give a complete classification of E_3-rings and prove that the class of non-trivial regular E_3-rings is empty.

Norma Zagaglia Salvi

A new topology for the interconnection of computing nodes in multiprocessors systems is the generalized Fibonacci cube.It can be embedded as a subgraph in the Boolean cube and it is also a supergraph of other structures. We prove that every edge of such a... see more