We propose a cooperative conceptual modelling environment in which two agents interact : the machine and the human expert. The former is able to extract knowledge from data using a symbolicnumeric machine learning system, and the latter is able to control the learning process by accepting and validating the machine results, or by criticizing those results or the explanation that the system produces on them. The improvment of the conceptual modelling relies on the cooperation between the two agents. Results obtained with our method on prediction of primate splice junctions sites in genetic sequences are far better than theses reported in the literature with other symbolic machine learning systems, and are as better as theses obtained with some artificial neural networks methods reported at present. But in opposite to neural networks which lack of argumentation, our system provides the user a plausible explanation of its prediction.