Jozef Schreier ``On finite base in topological groups''

One of the Ph.D. students in mathematics that belonged to Lviv Mathematical School of 1920?1939 years is Jozef Schreier. In the article, the authors provide an overview of main results of the unpublished thesis “On finite base in topological groups” by Jozef Schreier as well as the connection of the ideas of this work with modern investigations in the theory of topological groups and semigroups.