Abstract: 

This work of the famous mathematician, one of the founders of algebraic combinatorics, was read as a lecture at the conference dedicated to the memory of A. A. Leman and B. Yu. Weisfeiler. It had no references, and the author, unfortunately, did not manage to turn it into a full-fledged article. This was done for him by the members of the editorial board of JITCS A. A. Ivanov and M. Klin.

PP. 71-77.

DOI 10.14357/20718632200406