Algorithms for integration of unstructured mathematical documents into the common digital space of scientific knowledge

Algorithms for documents metadata formation of unstructured digital mathematical collections are proposed. They are based on the use of search queries to such open scientific resources of the World Wide Web as DBPedia, Wikidata, Wikipedia, Freebase. The developed algorithms made it possible to generate metadata in cases where it is very difficult or even impossible to extract it from document using text analytics methods. The results of applying these algorithms in the process of forming fundamental metadata sets of retro-collections included in the Lobachevskii Digital Mathematical Library ((Lobachevskii-DML, https://lobachevskii-dml.ru/) are presented. The composition of the main set of metadata complies with the requirements of the European Digital Mathematical Library (EuDML). The xml-language based on the Archive and Log Exchange Tag Package (NISO JATS) was used to represent the metadata