For the maintenance-management it is indispensable to apply the mathematical modelling, as quantity models in decision-making. Nowadays, the investigation of the uncertainty has become researchers’ area of interest in technology, especially in that area, where some measured data are needed to use. One of reasons, the precision or the reliability of the measurement can have or has an effect on decision-making and — finally — on results of the enforcement of the decision too. Decisions of the engineering management are often to use so-called linguistic variables, which have sources of newer significant uncertainties. Therefore the aim of the future domain of the author is methods of analysis, applying and improving, which have possibility to take notice of uncertainties and to investigate them. Hereby these expected results can be generalized, which make the acceptance of models, furthermore will be able to optimize cost. The study sums present scientific results from the area of mathematical modeling according to the subjectively selection of the author. In latter paper these results will be applied and put into practice for maintenance-management, as well as new methods will be developed.