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Publicações

Publicações por Pedro Manuel Ribeiro

2007

Plugging Computer Labs to the Grid

Autores
Ribeiro, P; Pereira, P; Lopes, L; Silva, F;

Publicação
IBERGRID: 1ST IBERIAN GRID INFRASTRUCTURE CONFERENCE PROCEEDINGS

Abstract
We present an architecture that allows the seamless configuration of computer labs to work as dedicated computing clusters during periods of user inactivity. The operation of the cluster is fully automated by making use of differentiated network booting and a job management system. We have prepared it to be plugged to a larger computational grid. We provide some preliminary performance results obtained.

2023

Evaluation of Regularization Techniques for Transformers-Based Models

Autores
Oliveira, HS; Ribeiro, PP; Oliveira, HP;

Publicação
Pattern Recognition and Image Analysis - 11th Iberian Conference, IbPRIA 2023, Alicante, Spain, June 27-30, 2023, Proceedings

Abstract

2023

Towards the Concept of Spatial Network Motifs

Autores
Ferreira, J; Barbosa, A; Ribeiro, P;

Publicação
COMPLEX NETWORKS AND THEIR APPLICATIONS XI, COMPLEX NETWORKS 2022, VOL 2

Abstract
Many complex systems exist in the physical world and therefore can be modeled by networks in which their nodes and edges are embedded in space. However, classical network motifs only use purely topological information and disregard other features. In this paper we introduce a novel and general subgraph abstraction that incorporates spatial information, therefore enriching its characterization power. Moreover, we describe and implement a method to compute and count our spatial subgraphs in any given network. We also provide initial experimental results by using our methodology to produce spatial fingerprints of real road networks, showcasing its discrimination power and how it captures more than just simple topology.

2021

Anti-Money Laundering Alert Optimization Using Machine Learning with Graphs

Autores
Eddin, AN; Bono, J; Aparício, D; Polido, D; Ascensão, JT; Bizarro, P; Ribeiro, P;

Publicação
CoRR

Abstract

2023

Improving the Characterization and Comparison of Football Players with Spatial Flow Motifs

Autores
Barbosa, A; Ribeiro, P; Dutra, I;

Publicação
COMPLEX NETWORKS AND THEIR APPLICATIONS XI, COMPLEX NETWORKS 2022, VOL 2

Abstract
Association Football is probably the world's most popular sport. Being able to characterise and compare football players is therefore a very important and impactful task. In this work we introduce spatial flow motifs as an extension of previous work on this problem, by incorporating both temporal and spatial information into the network analysis of football data. Our approach considers passing sequences and the role of the player in those sequences, complemented with the physical position of the field where the passes occurred. We provide experimental results of our proposed methodology on real-life event data from the Italian League, showing we can more accurately identify players when compared to using purely topological data.

2025

Multilayer horizontal visibility graphs for multivariate time series analysis

Autores
Silva, VF; Silva, ME; Ribeiro, P; Silva, F;

Publicação
DATA MINING AND KNOWLEDGE DISCOVERY

Abstract
Multivariate time series analysis is a vital but challenging task, with multidisciplinary applicability, tackling the characterization of multiple interconnected variables over time and their dependencies. Traditional methodologies often adapt univariate approaches or rely on assumptions specific to certain domains or problems, presenting limitations. A recent promising alternative is to map multivariate time series into high-level network structures such as multiplex networks, with past work relying on connecting successive time series components with interconnections between contemporary timestamps. In this work, we first define a novel cross-horizontal visibility mapping between lagged timestamps of different time series and then introduce the concept of multilayer horizontal visibility graphs. This allows describing cross-dimension dependencies via inter-layer edges, leveraging the entire structure of multilayer networks. To this end, a novel parameter-free topological measure is proposed and common measures are extended for the multilayer setting. Our approach is general and applicable to any kind of multivariate time series data. We provide an extensive experimental evaluation with both synthetic and real-world datasets. We first explore the proposed methodology and the data properties highlighted by each measure, showing that inter-layer edges based on cross-horizontal visibility preserve more information than previous mappings, while also complementing the information captured by commonly used intra-layer edges. We then illustrate the applicability and validity of our approach in multivariate time series mining tasks, showcasing its potential for enhanced data analysis and insights.

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