1,206 research outputs found
Topological properties of semigroup primes of a commutative ring
A semigroup prime of a commutative ring is a prime ideal of the semigroup
. One of the purposes of this paper is to study, from a topological
point of view, the space \scal(R) of prime semigroups of . We show that,
under a natural topology introduced by B. Olberding in 2010, \scal(R) is a
spectral space (after Hochster), spectral extension of \Spec(R), and that the
assignment R\mapsto\scal(R) induces a contravariant functor. We then relate
-- in the case is an integral domain -- the topology on \scal(R) with the
Zariski topology on the set of overrings of . Furthermore, we investigate
the relationship between \scal(R) and the space
consisting of all nonempty inverse-closed subspaces of \spec(R), which has
been introduced and studied in C.A. Finocchiaro, M. Fontana and D. Spirito,
"The space of inverse-closed subsets of a spectral space is spectral"
(submitted). In this context, we show that \scal( R) is a spectral retract of
and we characterize when \scal( R) is
canonically homeomorphic to , both in general and
when \spec(R) is a Noetherian space. In particular, we obtain that, when
is a B\'ezout domain, \scal( R) is canonically homeomorphic both to
and to the space \overr(R) of the overrings of
(endowed with the Zariski topology). Finally, we compare the space
with the space \scal(R(T)) of semigroup primes
of the Nagata ring , providing a canonical spectral embedding
\xcal(R)\hookrightarrow\scal(R(T)) which makes \xcal(R) a spectral retract
of \scal(R(T)).Comment: 21 page
A topological version of Hilbert's Nullstellensatz
We prove that the space of radical ideals of a ring , endowed with the
hull-kernel topology, is a spectral space, and that it is canonically
homeomorphic to the space of the nonempty Zariski closed subspaces of
Spec, endowed with a Zariski-like topology.Comment: J. Algebra (to appear
Rotation Estimation Based on Anisotropic Angular Radon Spectrum
In this letter, we present the anisotropic Angular Radon Spectrum (ARS), a novel feature for global estimation of rotation in a two dimension space. ARS effectively describes collinearity of points and has the properties of translation-invariance and shift-rotation. We derive the analytical expression of ARS for Gaussian Mixture Models (GMM) representing point clouds where the Gaussian kernels have arbitrary covariances. Furthermore, we developed a preliminary procedure for simplification of GMM suitable for efficient computation of ARS. Rotation between point clouds is estimated by searching of maximum of correlation between their spectra. Correlation is efficiently computed from Fourier series expansion of ARS. Experiments on datasets of distorted object shapes, laser scans and on robotic mapping datasets assess the accuracy and robustness to noise in global rotation estimation
On the collaboration uncapacitated arc routing problem
This paper introduces a new arc routing problem for the optimization of a collaboration scheme among carriers. This yields to the study of a profitable uncapacitated arc routing problem with multiple depots, where carriers collaborate to improve the profit gained. In the first model the goal is the maximization of the total profit of the coalition of carriers, independently of the individual profit of each carrier. Then, a lower bound on the individual profit of each carrier is included. This lower bound may represent the profit of the carrier in the case no collaboration is implemented. The models are formulated as integer linear programs and solved through a branch-and-cut algorithm. Theoretical results, concerning the computational complexity, the impact of collaboration on profit and a game theoretical perspective, are provided. The models are tested on a set of 971 instances generated from 118 benchmark instances for the Privatized Rural Postman Problem, with up to 102 vertices. All the 971 instances are solved to optimality within few seconds.Peer ReviewedPostprint (author's final draft
Pre-Alpine and Alpine deformation at San Pellegrino pass (Dolomites, Italy)
In this work, we present the geological map of the San Pellegrino pass, inserted in the
spectacular scenario of the Dolomiti region (Southern Alps, Italy), at a scale of 1:10.000 and
accompanied by geological cross-sections. The detailed distinction of lithological thin units
allowed to achieve a consistent interpretation of the local structural setting by drawing
brittle and ductile Alpine tectonic deformations. The differential deformation and structural
styles within the geological map are the result of the different rheological nature of volcanic
and sedimentary rocks, as well as of the superimposition of compressional Alpine tectonics
over Permo-Mesozoic extensional tectonic phases, and consequent reactivation of inherited
structures
PROVE DI COLTIVAZIONE BIOLOGICA DELLA PATATA IN AREALI MONTANI
Il mantenimento delle attività agricole nelle aree montane è indispensabile
per tutelare la stabilità del paesaggio e dell’assetto idrogeologico, ed è possibile
realizzarlo attraverso il rilancio della coltivazione della patata.
Il sito di coltivazione montano e le varietĂ autoctone sono in grado di indurre
un significativo miglioramento delle caratteristiche qualitative ed organolettiche
del prodotto. Questo può essere ulteriormente valorizzato da elementi quali la tipicità e la coltivazione biologica
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