Acknowledgments


The authors would like to let there thanks to their colaborators

Francisco de Assis Zampirolli e Joao Ricardo de Freitas Oliveira, who have implemented some workspaces for this tutorial.

The authors thank prof. Arnaldo Mandel, Douglas Vieira and Antonio Figueiredo for their help with the local networks of IME-USP and DCA-FEE-UNICAMP.

During the period of elaboration of this work, the authors have obtainded support of CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico) e FAPESP (Fuandacao de Amparo a Pesquisa do Estado de Sao Paulo).

Prof. Barrera has also been supported by Olivetti.