1. A processing method for a production system comprising a rule base for storing rules, each rule having a condition part and conclusion part, an actual database for storing fact data, and a processor, the processing method comprising the steps of: a) designating (i) at least a rule, (ii) fact data to be combined with the designated rule, and (iii) a conflict resolution strategy for resolving conflicts between instantiations obtained by combining said fact data and said at least a rule; b) with said processor, combining the condition part of said at least a rule with said designated fact data, in an order given by said conflict resolution strategy, to generate at least an instantiation; c) stopping the combining process performed in the combining step at a first success in the combining process; and d) with said processor, executing the conclusion part corresponding to the instantiation corresponding to the first success.