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Publicações

Publicações por LIAAD

2022

O eterno caso dos adjetivos temporais e aspetuais um contributo para a sua caracterização semântica

Autores
Ferreira, I; Cunha, LF; Leal, A; Silvano, P; Silva, F;

Publicação
Linguística: Revista de Estudos Linguísticos da Universidade do Porto

Abstract
The aim of this paper is to analyze the semantic behavior of adjectives that have been designated as temporal and aspectual in the literature, regarding the readings they can display. For this purpose, sixteen of these adjectives were selected and fifty occurrences of each one were randomly chosen and investigated. Overall, we observed a significant variety of readings associated with all the adjectives under scrutiny, which to greater or lesser degrees can express temporal, aspectual, temporo-aspectual values, and readings of qualificative and relational adjectives. This diversity of possible readings raises problems for proposals that intend to classify this group of adjectives in a static manner (i.e., without considering the context).

2021

Knee Point Detection in Water Absorption Curves: Hygric Resistance in Multilayer Building Materials

Autores
Azevedo, AC; Delgado, JMPQ; Guimarães, AS; Ribeiro, I; Sousa, R;

Publicação
Building Pathology and Rehabilitiation

Abstract
The moisture transfer process in multilayered building components with an interface is very different than the moisture transfer considered when having different materials/layers separately. Quantifying moisture transfer in multi-layered systems through numerical simulations is essential to predict the real behaviour of those building materials in contact with moisture, which depends on the climatic conditions. Unfortunately, the contact phenomenon is neglected in numerical simulations which compromise the feasibility of the results. In this work, the moisture transfer in multi-layered building components is analysed in detail, for perfect contact and hydraulic contact interface. The “knee point” was detected, numerically, in water absorption curves and the moisture-dependent interface resistance was quantified and validated for transient conditions. The methodology proposed to detect the “knee point” can be also used in the future for different multilayer materials with an interface, in order to obtain more correct maximum hygric resistance values, to be used in future numerical simulations. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021.

2021

Statistically Robust Evaluation of Stream-Based Recommender Systems

Autores
Vinagre, J; Jorge, AM; Rocha, C; Gama, J;

Publicação
IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING

Abstract
Online incremental models for recommendation are nowadays pervasive in both the industry and the academia. However, there is not yet a standard evaluation methodology for the algorithms that maintain such models. Moreover, online evaluation methodologies available in the literature generally fall short on the statistical validation of results, since this validation is not trivially applicable to stream-based algorithms. We propose a k-fold validation framework for the pairwise comparison of recommendation algorithms that learn from user feedback streams, using prequential evaluation. Our proposal enables continuous statistical testing on adaptive-size sliding windows over the outcome of the prequential process, allowing practitioners and researchers to make decisions in real time based on solid statistical evidence. We present a set of experiments to gain insights on the sensitivity and robustness of two statistical tests-McNemar's and Wilcoxon signed rank-in a streaming data environment. Our results show that besides allowing a real-time, fine-grained online assessment, the online versions of the statistical tests are at least as robust as the batch versions, and definitely more robust than a simple prequential single-fold approach.

2021

A Hybrid Recommender System for Improving Automatic Playlist Continuation

Autores
Gatzioura, A; Vinagre, J; Jorge, AM; Sànchez Marrè, M;

Publicação
IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING

Abstract
Although widely used, the majority of current music recommender systems still focus on recommendations' accuracy, user preferences and isolated item characteristics, without evaluating other important factors, like the joint item selections and the recommendation moment. However, when it comes to playlist recommendations, additional dimensions, as well as the notion of user experience and perception, should be taken into account to improve recommendations' quality. In this work, HybA, a hybrid recommender system for automatic playlist continuation, that combines Latent Dirichlet Allocation and Case-Based Reasoning, is proposed. This system aims to address "similar concepts" rather than similar users. More than generating a playlist based on user requirements, like automatic playlist generation methods, HybA identifies the semantic characteristics of a started playlist and reuses the most similar past ones, to recommend relevant playlist continuations. In addition, support to beyond accuracy dimensions, like increased coherence or diverse items' discovery, is provided. To overcome the semantic gap between music descriptions and user preferences, identify playlist structures and capture songs' similarity, a graph model is used. Experiments on real datasets have shown that the proposed algorithm is able to outperform other state of the art techniques, in terms of accuracy, while balancing between diversity and coherence.

2021

Time-Matters: Temporal Unfolding of Texts

Autores
Campos, R; Duque, J; Cândido, T; Mendes, J; Dias, G; Jorge, A; Nunes, C;

Publicação
ECIR (2)

Abstract
Over the past few years, the amount of information generated, consumed and stored on the Web has grown exponentially, making it impossible for users to keep up to date. Temporal data representation can help in this process by giving documents a sense of organization. Timelines are a natural way to showcase this data, giving users the chance to get familiar with a topic in a shorter amount of time. Despite their importance, little is known about their use in the context of single documents. In this paper, we present Time-Matters, a novel system to automatically explore arbitrary texts through temporal narratives in an interactive fashion that allows users to get insights into the relevant temporal happenings of a story through multiple components, including temporal annotation, storylines or temporal clustering. In contrast to classical timeline multi-document summarization tasks, we focus on performing text summaries of single documents with a temporal lens. This approach may be of interest to a number of providers such as media outlets, for which automatically building a condensed overview of a text is an important issue.

2021

TLS-Covid19: A New Annotated Corpus for Timeline Summarization

Autores
Pasquali, A; Campos, R; Ribeiro, A; Santana, BS; Jorge, A; Jatowt, A;

Publicação
ECIR (1)

Abstract
The rise of social media and the explosion of digital news in the web sphere have created new challenges to extract knowledge and make sense of published information. Automated timeline generation appears in this context as a promising answer to help users dealing with this information overload problem. Formally, Timeline Summarization (TLS) can be defined as a subtask of Multi-Document Summarization (MDS) conceived to highlight the most important information during the development of a story over time by summarizing long-lasting events in a timely ordered fashion. As opposed to traditional MDS, TLS has a limited number of publicly available datasets. In this paper, we propose TLS-Covid19 dataset, a novel corpus for the Portuguese and English languages. Our aim is to provide a new, larger and multi-lingual TLS annotated dataset that could foster timeline summarization evaluation research and, at the same time, enable the study of news coverage about the COVID-19 pandemic. TLS-Covid19 consists of 178 curated topics related to the COVID-19 outbreak, with associated news articles covering almost the entire year of 2020 and their respective reference timelines as gold-standard. As a final outcome, we conduct an experimental study on the proposed dataset over two extreme baseline methods. All the resources are publicly available at https://github.com/LIAAD/tls-covid19.

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