“…Let I be the set of vacancy identifiers; H is the set of specialization codes; S is the set of key skills in text format. Suppose is the set of vacancies; an online vacancy v is a 6-tuple v = (i, C, d, p, g, K ), where , is the subset of specialization codes, d is the vacancy published date, p is the text name of vacancy's position, g is the 4 HeadHunter API, https://dev.hh.ru 5 SimilarWeb: websites ranking, https://www.similarweb.com/top-websites/russian-federation/ category/jobs-and-career/jobs-and-employment 6 HeadHunter API: Specializations, https://api.hh.ru/specializations text description of the vacancy, is the subset of skills (in text format) for a particular vacancy.…”