Gladys Castillo João Gama Pedro Medas Adaptation to Drifting Concepts. 279-293 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2902&spage=279 2003 conf/epia/2003 EPIA db/conf/epia/epia2003.html#CastilloGM03