| 22/2001 |
Strongly Indefinite Functionals and multiple solutions of elliptic systems Djairo G. Figueiredo, Y. H. Ding We study existence and multiplicity of solutions of the elliptic system  rp-2001-22.pdf |
| 21/2001 |
On a semilinear elliptic problem without $(PS)$ condition Djairo G. Figueiredo, Yang Jianfu We establish an existence result for semilinear elliptic problems with the associated functional not satisfying the Palais-Smale condition. The nonlinearity of our problem fits none of conditions in \cite{AR}, \cite{dFLN} and \cite{GS1}. rp-2001-21.pdf |
| 20/2001 |
On the Existence and Shape of Least Energy Solutions for Some Elliptic Systems Andrés I. Ávila, Yang Jianfu We establish an existence result for strongly indefinite semilinear elliptic systems with Neumann boundary condition, and we study the limiting behavior of the positive solutions of the singularly perturbed problem. rp-2001-20.pdf |
| 19/2001 |
On maximal curves and unramified coverings Rainer Fuhrmann, Arnaldo Garcia, Fernando Torres We discuss sufficient conditions for a given curve to be covered by a maximal curve with the covering being unramified; it turns out that the given curve itself will be also maximal. We relate our main result to the question of whether or not a maximal curve is covered by the Hermitian curve. We also provide examples illustrating the results. rp-2001-19.pdf |
| 18/2001 |
An\'alise do desempenho do m\'etodo GMRES Marcos Eduardo Ribeiro do Valle Mesquita, Maria A. Diniz-Ehrhardt In this work, we are interested in the resolution of two kind of problems that have many practical applications. The first one is the resolution of a large linear system of equations, in which the coefficient matrix is sparse. We propose the iterative method GMRES (Generalized Minimal RESidual), introduced by Saad and Schultz, in 1986. At each iteration of this algorithm, one minimizes the residual norm in the Krylov subspace, using the Arnoldi method (equivalent to the Gram-Schimdt process) to compute an orthonormal basis for this subspace.The second problem is the resolution of nonlinear systems of equations. The classical Newton method is very attractive to solve this kind of problem, because it has fast convergence. But it requires the resolution of a linear system at each iteration, which can be too expensive. So, we propose the Inexact Newton method, which uses an iterative method to solve the linear equations. In this work, we combine the Newton method with GMRES applied to the linear system for the Newton step. Finally we present some numerical experiments in order to analyse the performance of Newton--GMRES. We use MATLAB codes written by C. T. Kelley, in 1995. rp-2001-18.pdf |
| 17/2001 |
Solving Generalized Nonlinear Complementarity Problems: Numerical Experiments on Polyhedral Cones Roberto Andreani, Ana Friedlander, Sandra A. Santos In a previous work, the minimization of a differentiable function subject to box constraints was proposed as a strategy to solve the generalized nonlinear complementarity problem (GNCP) defined on a polyhedral cone. Theoretical results that relate stationary points of the function that is minimized to the solutions of the GNCP were presented. These theoretical results show that local methods for box constrained optimization applied to the associated problem are efficient tools for solving the GNCP. In this work, numerical experiments are presented that encourage the use of this approach. rp-2001-17.pdf |
| 16/2001 |
Relative invariance for monoid actions Carlos J. Braga Barros Let $G$ be a topological group and $S\subset G$ a submonoid of $G$ acting on the topological space $M$. Let $J$ be a subset of $M$. Our purpose here is to study the subsets of $M$ which correspond, under the action of $S$, to the relative (with respect to $J$) invariant control sets for control systems [4]. The relation $x\thicksim y$ if $y\in {\rm cl}(Sx)$ and $x\in {\rm cl}(Sy)$ is an equivalence relation and the classes with respect to this relation with nonempty interior in $M$ are the control sets for the action of $S$. It is given conditions for the existence and uniqueness of relative invariant classes. As it was done for the control sets, we define an order in the classes and relate it to the relative invariant classes. We also show under certain condition that the relative invariant classes are relatively closed in $J$. rp-2001-16.pdf |
| 15/2001 |
Chain control sets and fiber bundles Carlos J. Braga Barros Let $S$ be a semigroup of homeomorphisms of a compact metric space $M$ and suppose that ${\cal F}$ is a family of subsets of $S$. This paper gives a characterization of the ${\cal F}$-chain control sets as intersection of control sets for the semigroups generated by the neighborhoods of the subsets in ${\cal F}$. We also study the behavior of ${\cal F}$-chain control sets on principal bundles and their associated bundles. rp-2001-15.pdf |
| 14/2001 |
Influence Diagnostics For Structural Erros-in-Variables Model Under The Student-t Distribution Manuel Galea, Heleno Bolfarine, Filidor E. Vilca-Labra rp-2001-14.pdf |
| 13/2001 |
Fibonacci Numbers and Partitions José Plínio O. Santos, Milos Ivkovic rp-2001-13.pdf |
