Abstract: The present invention provides a robot system for learning one or more new semantic relations in a knowledge base of physical skills. The system is configured to obtain knowledge on a physical skill by observing a demonstration, by a human user, of the physical skill, update the knowledge base with the obtained knowledge, generate a hypothesis of using the physical skill in a different context compared to a context of the demonstration by performing similarity considerations on the knowledge base using the obtained knowledge, present the hypothesis to the human user, receive a confirmation or a refusal from the human user with regard to the presentation of the hypothesis to the human user, and update the knowledge base according to the hypothesis in case of receiving the confirmation or discard the hypothesis in case of receiving the refusal.