"Algebra of program mixed execution"

The author informs that misprint corrections are airmailed today.

Thanks for the received books; account of the Department of Programming affairs and family news; interesting calculations of Ershov's working time

with V.E.Itkin.

Request to authorize the business trip to Erevan University

informing of the reasons for turning down the invitation; suggeston to invite V.E. Itkin instead

for the staff of Ershov's and Pottosin's laboratories