Institute of Informatics, Federal University of Goiás, Goiânia, Brazil. wellington@inf.ufg.br.|Institute of Informatics, Federal University of Goiás, Goiânia, Brazil. wellington@inf.ufg.br.|Institute of Informatics, Federal University of Goiás, Goiânia, Brazil. wellington@inf.ufg.br.|Institute of Informatics, Federal University of Goiás, Goiânia, Brazil. wellington@inf.ufg.br.|Institute of Informatics, Federal University of Goiás, Goiânia, Brazil. wellington@inf.ufg.br.