CHARACTERIZATION OF MODELS WITH DISCOUNTING
Among the widely used economic-mathematical models, dynamic programming plays an important role, and among them, models with discounting. The most famous example is the model for calculating the net present value (NPV) as an estimate of the efficiency of the investment project. In the article, it is clarified which features are distinguished by models with discounting among all models of dynamic programming. In models with discounting, the comparison of plans does not change when the time of the beginning of the implementation of plans changes, ie. there is a stability of the results of comparing plans. It is proved that if the results of comparing plans for 1 and 2 steps are stable in the dynamic programming model, then this model is a model with discounting. This theorem shows that the introduction of discounted functions for the estimation of the effect is justified only in stable economic conditions in which the orderliness of managerial decisions does not change from year to year. In other words, if at the beginning of the period under consideration the first solution is better than the second, then at all other times, up to the end of the period under consideration, the first solution is better than the second. Stable economic conditions are rarely found in the modern economy with its constant changes, including those caused by innovations. Therefore, the decision to choose (to implement) an investment project from a set of possible ones can not be based solely on the calculation of discounted project performance indicators, such as net present value and internal rate of return. Such indicators can only play a supporting role. Decide on the choice of an investment project for implementation is necessary on the basis of the whole range of social, technological, environmental, economic, political factors