The main objective of the paper is to develop a system of economic and mathematical models for managing the investment activity of the coal mining enterprise, including improving the principles and methods for analyzing the profitability of investment projects and the optimal allocation of investments. Therefore, the article addressing the following issues: to determine the objectives of investment activity in coal mining enterprises; to systematize and identify statistically significant factors influencing investment activity in coal mining enterprises -affecting investment in coal mines; to form an economic-mathematical model for determining the amount of money that a coalmining enterprise can allocate to investing; to form an economic-mathematical model for determining the enterprises profit as a result of the investment project implementation; -to demonstrate expediency and perspective of the complex of developed model's implementation, to check their practical efficiency; With the help of neural networks, a model was built based on 12 kinds of investment (9 kinds of investments into equipment, capital investment, portfolio investment, intangible assets investments) which are the most typical for a coal-mining enterprise. The method of optimization of investment allocation on a coal mine was developed, which, in contrast to the existing ones, determines the optimal investment volume, which helps to maximize profits for 12 investment models. As a result the method of optimization of investment allocation on a coal mine was developed, which, in contrast to the existing ones, determines the optimal investment volume, which helps to maximize profits for 12 investment models.

The work is devoted to the analysis of the main principles and approaches to the introduction of the circular economy concept at the state level. The article contains both the theoretical foundations of the introduction of the circular economy, the conceptual apparatus and the analysis of practical cases of the successful introduction of the principles in the global space. In addition, the main problems that may stand in the way of the successful implementation of the circular economy at the state level are outlined. The paper considers the main aspects of the introduction of the concept of circular economy at the state and regional levels. The conceptual apparatus of the circular economy is presented and illustrated, the differences and advantages in comparison with the generally accepted system of the linear economy are noted. Also, the structure of the circular economy at the micro, macro, and meso levels is considered in detail in the work, the key aspects of implementation in the spheres of production, consumption, waste management, and development support are noted. Considerable attention was paid in the study to the tools for the introduction of the circular economy both at the state and regional levels and at the level of other subjects of economic activity. The circular economy toolkit proposed for analysis was considered both in terms of the economic effect of its introduction, and from the point of view of the presence of a certain number of problems for each of the tools. The identified problems on the way to successful application of circular economy tools outlined the vector of further research in this direction with the aim of accelerating the transformation processes of the transition from a linear to a circular form of economy.

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Modern conditions of turbulence in the external economic environment require business structures not only to respond quickly to new challenges, but also to form scenario models of behaviour in order to maintain competitive market advantages based on an objective review of their own commercial potential and reserves. It is noteworthy that the internal risks of the business structure are the primary obstacle in the growth of the efficiency of the commercial structure and determine its level of profitability. The purpose of the research is to assess the factor of formation of biased management decisions and the features of their implementation as factors of reducing the manifestation of internal business risks. Indicated that the system of effective business management must always take into account the manifestation and pressure of internal risk due to a number of factors that cannot be accurately assessed. Modern methodology of project management and project management does not take into account the tool of biased decisions. Anti-crisis management is presented as a mandatory element of management knowledge. Therefore, the further development of management should focus on the adoption of biased management decisions and the development of mechanisms for their timely implementation.

The paper reviews the existing approaches to assessing investment projects at the regional level. Studies by both domestic and foreign authors are presented. The necessity of using an integrated approach in assessing regional investments is noted. The paper presents a scheme of indicators by which the assessment of regional investments is carried out. So, such indicators as: social efficiency, commercial efficiency and budget efficiency are highlighted. The purpose of the article is to identify the entire range of existing problems that arise when assessing regional investments with a view to their subsequent elimination. The whole complex of problems is presented in the form of a table where the problem is described, its brief description and directions for improvement. Thus, among the main problems, the following are highlighted: problems associated with the quantitative measurement of evaluating the effectiveness of investment projects; problems associated with assessing the risks of project implementation; problems associated with the choice of methods for calculating the effectiveness of an investment project; problems associated with the accuracy of financial and mathematical calculations; uncertainty issues; problems associated with the choice of indicators when building models for assessing the effectiveness of investments for the region. To solve certain problems, the author recommends such areas of improvement as: development of criteria for assessing the social significance of an investment project; application of modern economic and mathematical methods and models that would allow determining the influence of parametric indicators of regional investment projects on indicators of social efficiency; accounting in the model of the main macroeconomic indicators of the region's activity, both economic and social; in order to achieve accuracy in determining the effectiveness of an investment project in conditions of uncertainty, it is necessary to forecast changes in all factors that determine the implementation of an investment project at the regional level; To eliminate the existing contradictions about the optimal selection of factors when assessing the effectiveness of investments at the regional level, it is necessary to conduct a study to assess the significance of factors by means of economic and mathematical modeling. The work initiates further research towards the development of a new concept for assessing regional investments.