The subject of the study is the problem of adapting language models to scientific subject areas. The issues of expanding language models to mathematical subject areas are considered. It is proposed to use the knowledge graph of the subject area as a tool for `tuning' the language model. To build the knowledge graph, the ontology of the subject area of he semantic library of mathematical subject areas and their applications LibMeta is used. Navigation through the subject area is carried out using the knowledge graph and is limited by the terminology of the thesaurus and ontology links. This approach allows using the knowledge graph to create a digital assistant in a recommender system, an agent for a language model, and to feed mathematical text data to a language model.