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␈↓ ↓H␈↓␈↓βS␈↓∧ Artificial Intelligence Laboratory, STANFORD UNIVERSITY, Stanford, California 94305

␈↓ ↓H␈↓∧Telephone 415 497-4430␈↓ 
-July 2, 1979 




␈↓ ↓H␈↓Prof. Andrei P. Ershov
␈↓ ↓H␈↓Computation Center
␈↓ ↓H␈↓Novosibirsk 630090
␈↓ ↓H␈↓USSR

␈↓ ↓H␈↓Dear Andrei:

␈↓ ↓H␈↓        The␈α≡nal␈α
volume␈αof␈α
the␈αencyclopedia␈α
arrived␈αtoday.␈α It␈α
has␈αbeen␈α
almost␈αeleven␈α
years␈αsince
␈↓ ↓H␈↓the␈α∞subscription␈α∞started,␈α∞and␈α∞I␈α∞would␈α∞never␈α∞have␈α∞let␈α∞you␈α∞take␈α∞so␈α∞much␈α∞trouble␈α∞had␈α∞I␈α
supposed
␈↓ ↓H␈↓they␈αwould␈αcome␈αone␈αat␈αa␈αtime␈αover␈αsuch␈αa␈αlong␈αperiod.␈α Anyway␈αthanks␈αvery␈αmuch␈αfor␈αall␈αyour
␈↓ ↓H␈↓trouble.␈α I␈αhave␈αfound␈αthe␈αencyclopedia␈αvery␈αinformative␈αand␈αhave␈αfound␈αnumerous␈αoccasions␈αfor
␈↓ ↓H␈↓comparing␈αits␈αtreatment␈αof␈αa␈αsubject␈αwith␈αthat␈αof␈αthe␈αEncyclopedia␈αBritannica.␈α I␈αmust␈αsay␈αthat␈αin
␈↓ ↓H␈↓general␈αthe␈α
Britannica␈αis␈α
better,␈αbut␈α
I␈αhave␈αoften␈α
found␈αfacts␈α
in␈αthe␈α
Soviet␈αEncyclopedia␈αthat␈α
were
␈↓ ↓H␈↓not in the Britannica.

␈↓ ↓H␈↓        Is there any American book I can send you or bring you?

␈↓ ↓H␈↓        I␈α
will␈α
be␈α
at␈α
IBM␈αin␈α
Yorktown␈α
Heights␈α
between␈α
July␈α15␈α
and␈α
September␈α
1␈α
in␈α
their␈αvisiting
␈↓ ↓H␈↓professor program.

␈↓ ↓H␈↓        Under␈αseparate␈α
cover␈αI␈α
am␈αsending␈α
you␈αa␈α
copy␈αof␈α
a␈αnew␈α
approach␈αto␈α
proving␈αthe␈α
properties
␈↓ ↓H␈↓of sequential programs called Elephant.


␈↓ ↓H␈↓Best regards,



␈↓ ↓H␈↓John McCarthy
␈↓ ↓H␈↓Director
␈↓ ↓H␈↓Professor of Computer Science