Liara Aparecida dos Santos Leal Dalcidio Moraes Claudio Laira Vieira Toscani Paulo Blauth Menezes Approximation Problems Categories. 9-14 2005 conf/eurocast/2005 EUROCAST http://dx.doi.org/10.1007/11556985_2 db/conf/eurocast/eurocast2005.html#LealCTM05