Resume
This work is cataloged in the Scientific Portal. Officially published in Springer Proceedings in Mathematics & Statistics (2018). Referenced as: "Martinho, Alberto; Alves, Eduardo; Rodrigues, Ana Maria; Ferreira, José Soeiro".
The complete abstract and full text can be accessed directly at the official DOI: https://doi.org/10.1007/978-3-319-71583-4_15