Abstract
We present an epistemological analysis of the concept of algorithm that permits us to study the didactic transposition. We propose a model based on the notion of conception from the cK¢ model, more precisely on the notion of conception Cµ that aims to represent the conception from the point of view of the academic knowledge. We show how this notion, with an adapted definition of problem, allows us to describe conceptions, taking into account the diversity of representations of the concept algorithm and also its tool-object dialectic. Finally, we present some results we obtained about the didactic transposition in the French high school (lycée).