Scielo RSS <![CDATA[Proyecciones (Antofagasta)]]> vol. 23 num. 3 lang. es <![CDATA[SciELO Logo]]> <![CDATA[<B>ABELIAN AUTOMORPHISMS GROUPS OF SCHOTTKY TYPE</B>]]> We study the problem of lifting an Abelian group H of automorphisms of a closed Riemann surface S (containing anticonformals ones) to a suitable Schottky uniformization of S (that is, when H is of Schottky type). If H+ is the index two subgroup of orientation preserving automorphisms of H and R = S/H+, then H induces an anticonformal automorphism τ : R -> R. If τ has fixed points, then we observe that H is of Schottky type. If τ has no fixed points, then we provide a su.cient condition for H to be of Schottky type. We also give partial answers for the excluded cases <![CDATA[UNIFORM STABILIZATION OF A PLATE EQUATION WITH NONLINEAR LOCALIZED DISSIPATION]]> We study the existence and uniqueness of a plate equation in a bounded domain of Rn, with a dissipative nonlinear term, localized in a neighborhood of part of the boundary of the domain. We use techniques from control theory, the unique continuation property and Nakao method to prove the uniform stabilization of the energy of the system with algebraic decay rates depending on the order of the nonlinearity of the dissipative term. <![CDATA[<B>UNIFORM BOUNDEDNESS IN VECTOR - VALUED SEQUENCE SPACES</B>]]> Let µ be a normal scalar sequence space which is a K-space under the family of semi-norms M and let X be a locally convex space whose topology is generated by the family of semi-norms X. The space µ{X} is the space of all X valued sequences chi = {<FONT FACE=Symbol>c k</FONT>} such that {q(<FONT FACE=Symbol>c k</FONT>)} <FONT FACE=Symbol>Î</FONT>µ{X} for all q <FONT FACE=Symbol>Î</FONT> X. The space µ{X} is given the locally convex topology generated by the semi-norms <FONT FACE=Symbol>ðp</FONT>pq(chi) = p({q(<FONT FACE=Symbol>c k</FONT>)}), p <FONT FACE=Symbol>Î</FONT> X, q <FONT FACE=Symbol>Î</FONT> M. We show that if µ satisfies a certain multiplier type of gliding hump property, then pointwise bounded subsets of the â-dual of µ{X} with respect to a locally convex space are uniformly bounded on bounded subsets of µ{X} <![CDATA[<B>PARALLEL SYNCRHRONOUS ALGORITHM FOR NONLINEAR FIXED POINT PROBLEMS</B>]]> We give in this paper a convergence result concerning parallel synchronous algorithm for nonlinear fixed point problems with respect to the euclidean norm in Rn. We then apply this result to some problems related to convex analysis like minimization of functionals, calculus of saddle point, convex programming... <![CDATA[<B>COMPENSATORS FOR SINGULAR CONTROL SYSTEMS WITH DELAYS IN OUTPUTS</B>]]> In this paper we study the design of dynamic compensators for linear singular control systems described by the equation Ex &acute;(t) = Ax(t) + Bu(t) with time delayed observed output y(t) = Cx(t - r). The proposed compensators are applied to solve the regulator problem for the mentioned systems with controlled output z(t) = Dx(t). <![CDATA[<B>EXISTENCE OF SOLUTIONS FOR A DISCRETE NON LINEAR EIGENVALUE PROBLEM </B>]]> In this article we expose some existence results on the solutions of the discrete non linear boundary value problem derived from Fisher’s continuous partial di.erential equations in steady state <![CDATA[<B>EXISTENCE OF SOLUTIONS FOR UNILATERAL PROBLEMS WITH L1 DATA IN ORLICZ SPACES</B>]]> This article is concerned with the existence result of the unilateral problem associated to equations of the type Au + g(x, u,<FONT FACE=Symbol>Ñ</FONT>u) = f, in Orlicz spaces, where f <FONT FACE=Symbol>Î</FONT>L¹(omega), the term g is a nonlinearity having natural growth and satisfying the sign condition. Some stability and positivity properties of solutions are proved