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Publicações

Publicações por LIAAD

2006

Stackelberg leadership with demand uncertainty in a differentiated duopoly

Autores
Ferreira, F; Ferreira, F; Pinto, A;

Publicação
PROCEEDINGS OF THE 25TH IASTED INTERNATIONAL CONFERENCE ON MODELLING, IDENTIFICATION, AND CONTROL

Abstract
On a symmetric differentiated Stackelberg duopoly model in which there is asymmetric demand information owned by leading and follower firms, we show that the leading firm does not necessarily have advantage over the following one. The reason for this is that the second mover can adjust its output level after observing the realized demand, while the first mover chooses its output level only with the knowledge of demand distribution.

2006

The circle and the solenoid

Autores
Pinto, AA; Sullivan, D;

Publicação
DISCRETE AND CONTINUOUS DYNAMICAL SYSTEMS

Abstract
In the paper, we discuss two questions about degree d smooth expanding circle maps, with d >= 2. (i) We characterize the sequences of asymptotic length ratios which occur for systems with Holder continuous derivative. The sequences of asymptotic length ratios are precisely those given by a positive Holder continuous function s (solenoid function) on the Cantor set C of d-adic integers satisfying a functional equation called the matching condition. In the case of the 2-adic integer Cantor set, the functional equation is s(2x + 1) = s(x)/s(2x) 1 + 1s(2x-1) -1. We also present a one-to-one correspondence between solenoid functions and affine classes of exponentially fast d-adic tilings of the real line that are fixed points of the d-amalgamation operator. (ii) We calculate the precise maximum possible level of smoothness for a representative of the system, up to diffeomorphic conjugacy, in terms of the functions s and cr(x) = (1 + s(x))/(1 + (s(x + 1))(-1)). For example, in the Lipschitz structure on C determined by s, the maximum smoothness is C1+alpha for 0 < alpha <= 1 if and only if s is alpha-Holder continuous. The maximum smoothness is C2+alpha for 0 < alpha <= 1 if and only if cr is (1 + alpha)-Holder. A curious connection with Mostow type rigidity is provided by the fact that s must be constant if it is alpha-Holder for alpha > 1.

2006

Goodness-of-fit methods for the bipolar Watson distribution defined on the hypersphere (vol 76, pg 142, 2006)

Autores
Figueiredo, A; Gomes, P;

Publicação
STATISTICS & PROBABILITY LETTERS

Abstract

2006

Goodness-of-fit methods for the bipolar Watson distribution defined on the hypersphere

Autores
Figueiredo, A; Gomes, P;

Publicação
STATISTICS & PROBABILITY LETTERS

Abstract
The Watson distribution is frequently used for modeling axial data. In this paper, we present goodness-of-fit methods for the bipolar Watson distribution defined on the hypersphere. We analyze by simulation some questions concerning these tests: the adequacy of the asymptotic chi-square distribution used in the tests and the adequacy of using the tabulated critical values for the Kolmogorov-Smirnov statistic when the parameters of the bipolar Watson distribution are unknown. We illustrate these techniques with simulated data from this distribution.

2006

Two-way analysis of variance for data from a concentrated bipolar Watson distribution

Autores
Figueiredo, A;

Publicação
JOURNAL OF APPLIED STATISTICS

Abstract
The bipolar Watson distribution is frequently used for modeling axial data. We extend the one-way analysis of variance based on this distribution to a two-way layout. We illustrate the method with directional data in three dimensions.

2006

Discriminant analysis based on the Watson distribution defined on the hypersphere

Autores
Figueiredo, A; Gomes, P;

Publicação
STATISTICS

Abstract
The Watson distribution defined on the hypersphere is one of the most used distributions for modelling axial data. In this paper, we consider the discriminant analysis for axial data assumed to come from a mixture of Watson distributions defined on the hypersphere. We develop an optimal classification rule, which enables us to assign a new observation into one of several Watson subpopulations defined on the hypersphere. As the probabilities of misclassification cannot be calculated in closed form, we report on a simulation study to estimate, in some cases, the probabilities of misclassification and a distance between the two Watson subpopulations defined on the hypersphere. An illustration of our approach is provided using data defined on the sphere given in the literature.

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