Interaction between reactive and deliberative tasks for on-line decision-making

To get actual autonomous engines or systems, it is necessary to equip them with on-line decision-making mechanisms: computation of decisions that fit the current situation, performed in parallel with real execution. However, such a computation introduces a contradiction between requirements on the quality of the decision and on the time at which it will be delivered. This contradiction is all the stronger as decisionmaking may require intensive computing whose duration is not very well controlled. The solutions that are proposed in the literature to overcome this contradiction are often unsatisfactory, either from the point of view of the quality requirements, or from the one of the temporal requirements, most of the time from the one of the organisation and validation of the whole decision-making mechanism