Hugo Gonçalo Oliveira

PAPEL: A Dictionary-Based Lexical Ontology for Portuguese

This paper describes a project aimed at creating a lexical ontology extracted (semi) automatically from a large Portuguese general dictionary. Although using machine readable dictionaries to extract semantic information is not new, we believe this is the first attempt for the Portuguese language. The paper describes a (to be) freely available resource, dubbed PAPEL, explaining the process used and the tools developed, and illustrating it with one specific relation: Causation.

ECO and Onto.PT: a flexible approach for creating a Portuguese wordnet automatically

A wordnet is an important tool for developing natural language processing applications for a language. However, most wordnets are handcrafted by experts, which limits their growth. In this article, we propose an automatic approach to create wordnets by exploiting textual resources, dubbed ECO. After extracting semantic relation instances, identified by discriminating textual patterns, ECO discovers synonymy clusters, used as synsets, and attaches the remaining relations to suitable synsets. Besides introducing each step of ECO, we report on how it was implemented to create Onto.PT, a public lexical ontology for Portuguese. Onto.PT is the result of the automatic exploitation of Portuguese dictionaries and thesauri, and it aims to minimise the main limitations of existing Portuguese lexical knowledge bases.

Automatic discovery of fuzzy synsets from dictionary definitions

In order to deal with ambiguity in natural language, it is common to organise words, according to their senses, in synsets, which are groups of synonymous words that can be seen as concepts. The manual creation of a broad-coverage synset base is a time-consuming task, so we take advantage of dictionary definitions for extracting synonymy pairs and clustering for identifying synsets. Since word senses are not discrete, we create fuzzy synsets, where each word has a membership degree. We report on the results of the creation of a fuzzy synset base for Portuguese, from three electronic dictionaries. The resulting resource is larger than existing hancrafted Portuguese thesauri.

Second HAREM: New Challenges and Old Wisdom

Discussion of the Second HAREM: changes to the guidelines, introduction of new tracks, improvement of evaluation measures and description of the new evaluation resources.

Poetry Generation with PoeTryMe

PoeTryMe is a platform for the automatic generation of poetry, with a versatile architecture that provides a high level of customisation. The user can define features that go from the poem configuration and the line templates, to the initial seed words that will define a generation domain, and also the generation strategy. In this chapter, we introduce PoeTryMe’s architecture and describe how we used it to generate poetry in Portuguese, using natural language processing resources for this language as well as patterns that denote semantic relations in human-created poetry. After presenting the resources used with PoeTryMe, the problem of poetry generation is tackled incrementally, as our decisions are explained and illustrated, step-by-step. In the end, the objective features of the poems generated by the implemented strategies are compared, while the best-scoring poems are shown.

Erythroid Disturbances Before and After Treatment of Portuguese Psoriasis Vulgaris Patients

AbstractBackground: A few studies in psoriasis vulgaris patients have reported changes suggesting red blood cell (RBC) damage is linked to neutrophil activation, oxidative stress, and psoriasis worsening. Objective: The aim of this study was to evaluate erythroid disturbances in Portuguese psoriasis vulgaris patients, before, during, and after treatment. Methods: Across-sectional study (n = 73 patients vs 40 healthy control subjects) followed by a longitudinal study (n = 47 patients)was performed, with assessments before, and at 3, 6, and 12weeks of therapy (10 patients started topical treatment, 17 narrow-band UVB, and 20 photochemotherapy [psoralen plus UVA; PUVA]). Evaluations included hematologic data, total bilirubin levels,membrane-bound hemoglobin (MBH),membrane protein band 3 profile, total plasma antioxidant status (TAS), lipid peroxidation (thiobarbituric acid [TBA] assay), elastase, lactoferrin, and C-reactive protein (CRP). Results: Before treatment, patients presented with higher leukocyte/neutrophil and reticulocyte counts, elastase, lactoferrin, TBA, TBA/TAS, reticulocyte production index, total bilirubin and MBH values, lower RBC and hematocrit, higher percentages of high-molecular-weight aggregates, and lower percentages of band 3 monomer. After treatment, we observed a reversal in most of the parameters. However, patients still presented with values suggestive of accelerated RBC damage, removal, and production, as most of the parameters were still higher than those in the control group; the same occurred with CRP. Conclusion: Our data suggest that psoriasis vulgaris triggers an inflammatory response, with release of acutephase reactants, reactive oxygen species, cationic proteins, and proteases, leading to enhanced RBC damage/ aging and, ultimately, to enhanced RBC removal. These assumptions were strengthened by the observation that, with treatment, all of these changeswere reversed, the inflammation was reduced, the production of reticulocytes was increased, and the RBCs presented changes usually observed in younger/less damaged RBCs. These erythroid changes were enhanced with PUVA therapy, probably due to the more pronounced clearing of the lesions, as suggested by Psoriasis Area and Severity Index (PASI) scores. Finally, after treatment, a residual inflammation still persisted that might contribute to the observed erythroid disturbances.

Integrating lexical-semantic knowledge to build a public lexical ontology for portuguese

Onto.PT is a new public wordnet-like lexical ontology for Portuguese. To make its creation faster and to deal with information sparsity, Onto.PT is created automatically and integrates information extracted from existing lexical resources. After introducing Onto.PTs construction approach, this paper gives a closer look on this resource and provides information on its availability.

LemPORT: a High-Accuracy Cross-Platform Lemmatizer for Portuguese

Although lemmatization is a very common subtask in many natural language processing tasks, there is a lack of available true cross-platform lemmatization tools specifically targeted for Portuguese, namely for integration in projects developed in Java. To address this issue, we have developed a lemmatizer, initially just for our own use, but which we have decided to make publicly available. The lemmatizer, presented in this document, yields an overall accuracy over 98% when compared against a manually revised corpus.

CONTO.PT: Groundwork for the Automatic Creation of a Fuzzy Portuguese Wordnet

There are several lexical resources available for the computational processing of Portuguese, organised differently and created by different people with different approaches and limitations. This paper presents the first experiments towards the exploitation of seven of those resources in the automatic creation of a large wordnet, where numerical scores are assigned to the inclusion of words in synsets and to the connection of synsets by semantic relations. Experiments confirm that a large wordnet can indeed be created and, to some extent, computed scores can be used as a confidence measure, which will enable the users to select only a portion of the resource, depending on the needs of their application on quantity and quality of lexical-semantic knowledge.

Towards the automatic enrichment of a thesaurus with information in dictionaries

Regarding that information in broad-coverage knowledge bases, such as thesauri, is usually incomplete, merging information from different sources is an alternative to amplify coverage. We propose a method for the enrichment of a thesaurus with information acquired automatically from dictionaries. First, synonymy pairs are extracted. Then, these pairs are assigned to the most similar candidate synsets. Finally, the remaining pairs are the target of clustering to identify new synsets. After selecting the adequate experimentation settings, this method was applied to enrich a Portuguese thesaurus with synonyms extracted from three dictionaries, which resulted in TRIP, a larger and broader thesaurus with new words and concepts. The steps towards the creation of this new thesaurus and its evaluation are described here.