Revistas académicas de la Universidad Católica del Norte
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Spectra of related graphs and self-reproducing polyhedra
No full textlf G is a d-valent graph, the eigenvalues of the adjacency matrix of G determine those of the line graph, the subdivision graph and the graph made by replacing vertices with complete graphs. A property of the eigenvectors of the graphs of certain regular polyhedra is then seen to carry over to some truncationsof the polyhedra
Propiedades de invarianza de trayectorias para sistemas de control lineales
No full textEste trabajo está dedicado al estudio de algunas propiedades geométricas de trayectorias en sistemas de control lineales invariantes del tipo:x(t) = A x(t) + B u(t)donde x(t) en Rn representa el estado, u(t) en Rm la acción de control y tanto A como B representan matrices de órdenes apropiados
Algunos invariantes para álgebras báricas que satisfacen (x²)² = w(x)³x*
No full textEn [1] y [2] se define el concepto de E-ideal de una álgebra bárica (A,w) asociada a un train polinomio p(x), como también clase de equivalencia de train polinomios sobre una subclase ? de álgebras báricas. Se probó que para las álgebras que satisfacen la identidad ( x²)² = w ( x )³ x sólo existen tres clases de equivalencia de train polinomios, es decir, estas álgebras sólo contienen tres E-ideales. El cálculo de los E-ideales, en general, es complicado ya que para hacerlo se debe considerar potencias (principales) de un elemento arbitrario de la álgebra. Usando E -ideales de una álgebra bárica es posible obtener algunos invariantes de ella.En este trabajo, probamos que es suficiente considerar elementos de A de peso 1 para generar los E -ideales, simplificando el cálculo sustancialmente.Usando los E-ideales de A generados por elementos .de peso cero, obtenemos nuevos invariantes para las álgebras que satisfacen (x²)² = w (x)³ x
A characterization of Lorentz-improving measures
No full textLet G be an infinite compact abelian group and let ? denote its dual group. A borel measure µ on G is called Lorentz-improving if there existe p, q1, and q2, where 1 < p < ? and 1 ? q1 ? q2 ? ?, such that µ * L (p, q2) ? L (p, q1). A detailed exposition of our recent characterization of Lorentz-improving measures is presented here. In this result Lorentz-improving measures are characterized in terms of the size of the sets {? ? ? : ? µ (?) ? > ? } and in terms of n-fold convolution powers. This characterization is analogous to a known characterization of LP-improving measures due to Hare
Closed Riemann surfaces with dihedral groups of conformal automorphisms
No full textIn these notes we show that if H is a group of conformal automorphisms, isomorphic to a dihedral group, acting free fixed points on a closed Riemann surface S, then there is a Schottky uniformization of S for which H lifts. We also give an explicit example of a dihedral group for which the above lifting property fails, showing in this way that condition (A) of [4] is not sufficient in general
On k*-radical in BCI-algebras
No full textIn (2] the notion of nil radical in BCI-algebras was introduced and various properties are developed in [3]. Further, several results on nil ideals were obtained in [4] and [5]. The aim of this paper is to study and investigate some properties of k*- radicals in BCI-algebras. The notion of k*- semiprime ideal is introduced
?-hyperelliptic Riemann surfaces
No full textWe give some characterizations of ? -hyperelliptic Riemann surfaces of genus ? ? 2, that is, pairs (S, j) where S is a closed Riemann surface of genus ? and j : S ? S is a conformal involution with exactly 2? + 2 - 4? fixed points. These characterizations are given by Schottky groups, special hyperbolic polygons and algebraic curves.These can be seen as generalizations of the works [5] and [11]
Positive solutions for the 1-dimensional generalized p-Laplacian involving a real parameter
No full textIn this paper we study existence and multiplicity of positive solutions of the Dirichlet proble
