INF - Artigos publicados em periódicos
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Navegando INF - Artigos publicados em periódicos por Autor "Barbosa, Rommel Melgaço"
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Item A characterisation of cubic parity graphs(2003) Barbosa, Rommel Melgaço; Ellingham, Mark NormanA graph is Zm-well-covered if all maximal independent sets have the same cardinality modulo m. Zm-well-covered graphs generalise well-covered graphs, those in which all independent sets have the same cardinality. Z2- well-covered graphs are also called parity graphs. A characterisation of cubic well-covered graphs was given by Campbell, Ellingham and Royle. Here we extend this to a characterisation of cubic Zm-well-covered graphs for all integers m ≥ 2; the most interesting case is m = 2, cubic parity graphs. Our main technique involves minimal non-well-covered graphs, and allows us to build our characterisation as an extension of the existing characterisation of cubic well-covered graphs.Item Produtos de grafos Zm-bem-cobertos(2012) Barbosa, Rommel Melgaço; Santana, Márcia Rodrigues CappelleItem The importance of word-final vowel duration for non-native portuguese speaker identification by means of support vector machines(2014) Franks, Suzanne; Barbosa, Rommel MelgaçoThis article studies the acoustic characteristics of some oral vowels in tonic syllables of Brazilian Portuguese (BP) and which acoustic features are important for classifying native versus non-native speakers of BP. We recorded native and non-native speakers of BP for the purpose of the acoustic analysis of the vowels [a], [i], and [u] in tonic syllables. We analyzed the acoustic parameters of each segment using the Support Vector Machines algorithm to identify to which group, native or non-native, a new speaker belongs. When all of the variables were considered, a precision of 91% was obtained. The two most important acoustic cues to determine if a speaker is native or non-native were the durations of [i] and [u] in a word-final position. These findings can contribute to BP speaker identification as well as to the teaching of the pronunciation of Portuguese as a foreign language.