The author writes about his work “On transformation of programs written in Algol” written under the influence of the paper by Ershov and Lyapunov “On formalization of the ‘program’ notion” and asks Ershov for his opinion.

Thanks for the photos and books; account of the cufrrent affairs; hopes for a meeting in Moscow

Consent to be an official opponent of A.P. Ershov’s PhD thesis “Operator algorithms”.

Congratulations with the status as an acknowlegment of Ershov's personal achievements as a scientist and A.A. Lyapunov successor

Covering letter and the review by A.A. Liapunov of Tseitin’s scientific paper.

Regretting that Ershov could not come to the USA, and sending interesting papers from the last conferences

on the advice by Prof. Ottinger the author sends his paper "Some Applications of Logical Syntax to Digital ComputerProgramming" to A.A. Liapunov and asks for the opinion. Apparently, since in a year the letter got to Ershov, Liapunov asked him to look at the paper.