The theoretical computer science went through enormous development in the past decades. His results due to the widespread use of computers infl uence our daily work without the use of it we cannot imagine our life already today. But perhaps few people think that talented Hungarian mathemati cal generation worked in 20 and 30 years of 20. Century without whose acti vity these applications could not have come into exist. In our paper we present the results of Pál Erdős and along with a new generati on of mathemati cal chapter openers, which developed common theory through research and which become since the basis of computer science and informati on theory.