Functions of Borders and Delimitation of the Basic Concepts of Theoretical Limology

— The development of limology as an interdisciplinary scientific direction, not only in depth, but also in breadth due to the involvement of new types and forms of borders in research in various sciences, has led to ambiguity and uncertainty of many concepts and terms used in studying borders and related properties and processes. In recent decades, both in foreign and Russian publications, the political science concept of limology has dominated, which is a reflection of the modern mainstream aimed at studying state borders and related borderland and cross-border phenomena. In foreign limology, the term border studies is widespread, which reflects limological studies mainly in the social sciences and humanities. This approach narrows the concept and problems of limology as a science of the borders of a diverse nature. This determines the relevance of the formation of such a theoretical limology, which is defined as a scientific interdisciplinary direction that develops general approaches, principles and methods for analyzing the spatial borders of various types and hierarchical levels outside their object specifics. The basic problems of theoretical limology in this sense can be the development of a general conceptual apparatus common to all sciences, a set of specific modes of border delimitation; ordering approaches to the allocation of border functions; development of general foundations for their systematization and approaches to studying border and cross-border phenomena. An important role in ordering the basic limological concepts and terms is played by interdisciplinary research and ordering of boundary functions with the allocation of not only contact and barrier functions, but division, relationship, transit, and certain other functions. Their different combinations for homogeneous and connection in their territorial structure areas/territories allows us to give a more meaningful idea of borderland and cross-border phenomena.