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1. a gap between user and developer: the user has great difficulties in presenting his requirements and (expert) knowledge in such a way that the developer can understand them (user's model <-> developer's model).

2. a gap between developer and software system: the developer has great difficulties in putting into a system model the (expert) knowledge and the requirements of the user (developer's model <-> system model).

3. a gap between software system and user: the system is not well enough adapted to the user's expectations (system model <-> user's model).

- This shows that the steps taken in modelling must be improved. But how ?

- I think that the most important thing to do if we want to improve the steps taken in modelling is to address the problem of the foundations of modelling.

- To deal with this problem I will present in the following an analysis of the foundations of modelling in SW-Engineering in the light of Kant's theory of modelling.

- But before we do this, let us first have a short look at Kant, his age, life and work as a preparation to what will follow.