A unified approach to descriptive and prescriptive concepts in uncertain decision systems

The first purpose of this paper is to present shortly an idea of soft variables and evaluating functions as a tool for the unification and generalisation of decision making problems in control systems with a static plant. The random variables, uncertain variables and fuzzy descriptions are considered here as special cases of the descriptions based on the soft variables. The second purpose of the paper is to present the results concerning the relations between the descriptive approach (decisions based on the knowledge of the plant) and the prescriptive approach (decisions based directly on the knowledge of the decision making). The main result presented here in a rough form is called a principle of equivalency.