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Publications

2011

Focal decomposition, renormalization and semiclassical physics

Authors
de Carvalho, CAA; Peixoto, M; Pinheiro, D; Pinto, AA;

Publication
JOURNAL OF DIFFERENCE EQUATIONS AND APPLICATIONS

Abstract
We review some recent results concerning a connection between focal decomposition, renormalization and semiclassical physics. The dynamical behaviour of a family of mechanical systems which includes the pendulum at small neighbourhoods of the equilibrium but after long intervals of time can be characterized through a renormalization scheme acting on the dynamics of this family. We have proved that the asymptotic limit of this renormalization scheme is universal: it is the same for all the elements in the considered class of mechanical systems. As a consequence, we have obtained an asymptotic universal focal decomposition for this family of mechanical systems which can now be used to compute estimates for propagators in semiclassical physics.

2011

Metaheuristics for the Asymmetric Hamiltonian Path Problem

Authors
Pedroso, JP;

Publication
NUMERICAL METHODS AND APPLICATIONS

Abstract
One of the most important, applications of the Asymmetric Hamiltonian Path Problem is in scheduling. In this paper we describe a variant of this problem, and develop 1)011) a mathematical programming formulation and simple metaheuristics for solving it The formulation is based on a transformation of the input, data, in such a way that a standard mathematical programming model for the Asymmetric: Travelling Salesman Problem can be used on this slightly different problem. Two standard metaheuristics for the asymmetric travelling salesman are proposed and analysed on this variant: repeated random construction followed by local search with the 3-Exchange neighbourhood. and iterated local search based on the same neighbourhood and on a 4-Exchange perturbation. The computational results obtained show the interest, and the complementary merits of using a mixed-integer programming solver and an approximative method for the solution of this problem.

2011

Construction, instantiation and analysis of a business ecosystem for autonomic future networks

Authors
Gonçalves, V; Stamatelatos, M; Manzalini, A; Fuentes Arenaz, B; Gruber, M; Destré, C; Delaere, S; Ciavaglia, L;

Publication
2011 15th International Conference on Intelligence in Next Generation Networks, ICIN 2011

Abstract
Design, deployment and operations of future networks are expected to tackle a diverse range of business and technical challenges, such as how to empower networks with features of self-adapting to dynamic context and users' requirements, allowing for the emergence of disruptive business models and new industrial ecosystems. This paper focuses on defining and analysing two business scenarios in order to study the impacts of introducing autonomic networks. By identifying the business roles and relationships between them and business and strategic issues that may arise, we aim at establishing an overarching business ecosystem and a common reference model reflecting the challenges and opportunities of autonomic networking. © 2011 IEEE.

2011

Flexible heuristics miner (FHM)

Authors
Weijters, AJMM; Ribeiro, JTS;

Publication
IEEE SSCI 2011: Symposium Series on Computational Intelligence - CIDM 2011: 2011 IEEE Symposium on Computational Intelligence and Data Mining

Abstract
One of the aims of process mining is to retrieve a process model from a given event log. However, current techniques have problems when mining processes that contain nontrivial constructs, processes that are low structured and/or dealing with the presence of noise in the event logs. To overcome these problems, a new process representation language is presented in combination with an accompanying process mining algorithm. The most significant property of the new representation language is in the way the semantics of splits and joins are represented; by using so-called split/join frequency tables. This results in easy to understand process models even in the case of non-trivial constructs, low structured domains and the presence of noise. This paper explains the new process representation language and how the mining algorithm works. The algorithm is implemented as a plug-in in the ProM framework. An illustrative example with noise and a real life log of a complex and low structured process are used to explicate the presented approach. © 2011 IEEE.

2011

On the series expansion of the spatial SIS evolution operator

Authors
Martins, J; Aguiar, M; Pinto, A; Stollenwerk, N;

Publication
JOURNAL OF DIFFERENCE EQUATIONS AND APPLICATIONS

Abstract
For the spatial stochastic susceptible-infected-susceptible model, we consider the perturbative series expansion of the gap between the dominant and subdominant eigenvalues of the evolution operator. We compute explicitly the first terms of the series expansion of the gap with difference equations for the calculation of states.

2011

Hybridization of Institutions

Authors
Martins, MA; Madeira, A; Diaconescu, R; Barbosa, LS;

Publication
Algebra and Coalgebra in Computer Science - 4th International Conference, CALCO 2011, Winchester, UK, August 30 - September 2, 2011. Proceedings

Abstract
Modal logics are successfully used as specification logics for reactive systems. However, they are not expressive enough to refer to individual states and reason about the local behaviour of such systems. This limitation is overcome in hybrid logics which introduce special symbols for naming states in models. Actually, hybrid logics have recently regained interest, resulting in a number of new results and techniques as well as applications to software specification. In this context, the first contribution of this paper is an attempt to 'universalize' the hybridization idea. Following the lines of [15], where a method to modalize arbitrary institutions is presented, the paper introduces a method to hybridize logics at the same institution-independent level. The method extends arbitrary institutions with Kripke semantics (for multi-modalities with arbitrary arities) and hybrid features. This paves the ground for a general result: any encoding (expressed as comorphism) from an arbitrary institution to first order logic (FOL ) determines a comorphism from its hybridization to FOL. This second contribution opens the possibility of effective tool support to specification languages based upon logics with hybrid features. © 2011 Springer-Verlag.

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