Vol. 22 Num. 2 (2002) Richard Noss Mathematical epistemologies at work2 Luis Radford The seen, the spoken and the written: a semiotic approach to the problem of objectification of mathematical knowledge14 Helen Featherstone , Jay Featherstone "The word I would use is aesthetic": reading David Hawkins24 Lara Alcock , Adrian Simpson Definitions: dealing with categories mathematically28 Nathalie Gaudin Conceptions de fonction et registres de représentation: étude de cas au lycée35