126,546 research outputs found
Connected subgroups of SO(2,n) acting irreducibly on R^{2,n}
No full textWe classify all connected subgroups of SO(2, n) that act irreducibly on R^{2, n
Omosessualità e diritto: cosa importa allo stato dell’orientamento sessuale dei suoi cittadini?
No full textAtlante idrogeologico della Sardegna (scala 1:100.000)
No full textTipi e gradi di permeabilità delle principali formazioni litologiche della Sardegna riportati su carte alla scala 1:100.000 (27 tavole); ubicazione e caratteristiche idrogeologiche di pozzi, perforazioni e sorgenti considerati nello studio; curve piezometriche in formazioni alluvionali e non alluvionali. Lavoro eseguito nell'ambito del progetto speciale n° 25 della Cassa per il Mezzogiorno "Ricerche idriche sotterranee in Sardegna"
Minimal Immersions of Kahler manifolds into Euclidean Spaces
No full textIt is proved here that a minimal isometric immersion of a Kähler-Einstein or homogeneous Kähler-manifold into an Euclidean space must be totally geodesic
Legislazione regionale siciliana e controllo di costituzionalità
No full textil lavoro è suddiviso in due parti: prima parte di Giuseppe Verde , circa 150 pagine. Seconda parte di Giovanni Scala, circa 150 pagine.
Nella prima parte si ricostruisce l'andamento della legislazione regionale Siciliana con una particolare attenzione al sistema delle fonti. Nella seconda parte si ricostruisce lo svolgimento del controllo di costituzionalità cui è sottoposta la legislazione regionale Siciliana, alla luce dell'art. 10 della Legge costituzionale n. 3/2001 e della giurisprudenza costituzionale
A variational approach to single crystals with dislocations
No full textWe study the graphs of maps u : Omega -> R-3 whose curl is an integral 1-current with coefficients in Z(3). We characterize the graph boundary of such maps under a suitable summability property. We apply these results to study a three-dimensional single crystal with dislocations forming general one-dimensional clusters in the framework of finite elasticity. By virtue of a variational approach, a free energy depending on the deformation field and its gradient is considered. The problem we address is the joint minimization of the free energy with respect to the deformation field and the dislocation lines. We apply closedness results for graphs of torus-valued maps, seen as integral currents and, from the characterization of their graph boundaries, we are able to prove existence of minimizers
Variational evolution of dislocations in single crystals
No full textIn this paper, we provide an existence result for the energetic evolution of a set of dislocation lines in a three-dimensional single crystal. The variational problem consists of a polyconvex stored elastic energy plus a dislocation energy and some higher-order terms. The dislocations are modeled by means of integral one-currents. Moreover, we discuss a novel dissipation structure for such currents, namely the flat distance, that will serve to drive the evolution of the dislocation clusters
Analytic and geometric properties of dislo- cation singularities
No full textThis paper deals with the analysis of the singularities arising from the solutions of the problem, where F is a 3 × 3 matrix-valued Lp-function ($1les p) and μ a 3 × 3 matrix-valued Radon measure concentrated in a closed loop in 3, or in a network of such loops (as, for instance, dislocation clusters as observed in single crystals). In particular, we study the topological nature of such dislocation singularities. It is shown that, the absolutely continuous part of the distributional gradient Du of a vector-valued function u of special bounded variation. Furthermore, u can also be seen as a multi-valued field, that is, can be redefined with values in the three-dimensional flat torus 3 and hence is Sobolev-regular away from the singular loops. We then analyse the graphs of such maps represented as currents in × 3 and show that their boundaries can be written in term of the measure μ. Readapting some well-known results for Cartesian currents, we recover closure and compactness properties of the class of maps with bounded curl concentrated on dislocation networks. In the spirit of previous work, we finally give some examples of variational problems where such results provide existence of solutions
Extended letterplace correspondence for nongraded noncommutative ideals and related algorithms
No full textLet K be the free associative algebra generated by a finite or a countable number of variables x_i . The notion of “letterplace correspondence” introduced in [R. La Scala and V. Levandovskyy, Letterplace ideals and non-commutative Grobner bases, J. Symbolic Comput. 44 (2009) 1374–1393; R. La Scala and V. Levandovskyy, Skew polynomial rings, Grobner bases and the letterplace embedding of the free associative algebra, J. Symbolic Comput. 48 (2013) 110–131] for the graded (two-sided) ideals of K is extended in this paper also to the nongraded case. This amounts to the possibility of modelizing nongraded noncommutative presented algebras by means of a class of graded commutative algebras that are invariant under the action of the monoid N of natural numbers. For such purpose we develop the notion of saturation for the graded ideals of K, where t is an extra variable and for their letterplace analogues in the commutative polynomial algebra K[x_ij , t_j ], where j ranges in N. In particular, one obtains an alternative algorithm for computing inhomogeneous noncommutative Grobner bases using just homogeneous commutative polynomials. The feasibility of the proposed methods is shown by an experimental implementation developed in the computer algebra system Maple and by using standard routines for the Buchberger algorithm contained in Singular
Geometry applications of irreducible representations of Lie Groups
No full textIn this note we give proofs of the following three algebraic facts which have applications in the theory of holonomy groups and homogeneous spaces: Any irreducibly acting connected subgroup G \subset Gl(n,\rr) is closed. Moreover, if admits an invariant bilinear form of Lorentzian signature, is maximal, i.e. it is conjugated to . We calculate the vector space of -invariant symmetric bilinear forms, show that it is at most -dimensional, and determine the maximal stabilizers for each dimension. Finally, we give some applications and present some open problem
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