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␈↓ ↓H␈↓␈↓βS␈↓∧ Artificial Intelligence Laboratory, STANFORD UNIVERSITY, Stanford, California 94305
␈↓ ↓H␈↓∧Telephone 415 497-4430␈↓ 	↑February 14, 1976




␈↓ ↓H␈↓Prof. H. Yamada
␈↓ ↓H␈↓Department of Information Science
␈↓ ↓H␈↓Faculty of Science
␈↓ ↓H␈↓University of Tokyo
␈↓ ↓H␈↓Tokyo, Japan

␈↓ ↓H␈↓Dear Professor Yamada:

␈↓ ↓H␈↓        I␈α↔am␈α↔happy␈α↔to␈α↔recommend␈α↔Professor␈α↔Shigeru␈α↔Igarashi␈α↔for␈α↔a␈α↔Professorship␈α_in␈α↔the
␈↓ ↓H␈↓Department␈αof␈αInformation␈αScience␈αat␈αTokyo␈αUniversity.␈α The␈αmain␈αbasis␈αof␈αmy␈αrecommendation
␈↓ ↓H␈↓is␈α⊂Igarashi's␈α⊂work␈α⊂in␈α⊂the␈α⊂mathematical␈α⊂structure␈α⊂of␈α⊂computer␈α⊂programs␈α⊂as␈α⊂associated␈α⊂with␈α⊂the
␈↓ ↓H␈↓problem␈α
of␈α
proving␈α
that␈α
programs␈α
meet␈α
their␈α
speci≡cations.␈α
 Igarashi's␈α
PhD␈α
dissertation␈α
in␈α
1964
␈↓ ↓H␈↓was␈α
one␈α∞of␈α
the␈α
earliest␈α∞papers␈α
in␈α∞this␈α
≡eld,␈α
and␈α∞the␈α
approach␈α∞he␈α
took␈α
at␈α∞that␈α
time␈α∞owed␈α
almost
␈↓ ↓H␈↓nothing␈α∂to␈α⊂the␈α∂small␈α∂amount␈α⊂of␈α∂work␈α⊂that␈α∂had␈α∂been␈α⊂done␈α∂previously.␈α∂ I␈α⊂consider␈α∂his␈α⊂work␈α∂in
␈↓ ↓H␈↓mathematical␈αtheory␈αof␈αcomputation␈αthe␈αbest␈αdone␈αand␈αJapan␈αand␈αin␈αsustained␈αproductivity␈αhe␈αis
␈↓ ↓H␈↓in the same class as Rod Burstall and Zohar Manna.

␈↓ ↓H␈↓        We␈αwere␈αfortunate␈αin␈αhaving␈αhim␈αvisit␈αthe␈αStanford␈αArti≡cial␈αIntelligence␈αLaboratory␈αfor␈αa
␈↓ ↓H␈↓year␈α
on␈αtwo␈α
separate␈αoccasions␈α
and␈αbecame␈α
familiar␈αwith␈α
his␈αwork␈α
and␈αpersonality.␈α
 In␈αaddition␈α
to
␈↓ ↓H␈↓that,␈αI␈αvisited␈αKyoto␈αUniversity␈αfor␈αthree␈αmonths␈αin␈αthe␈αSpring␈αof␈α1975␈αand␈αhad␈αthe␈αopportunity
␈↓ ↓H␈↓to observe how he helped the younger people there and guided their work.

␈↓ ↓H␈↓        I␈α
don't␈α
have␈α∞Igarashi's␈α
bibliography␈α
in␈α∞front␈α
of␈α
me,␈α∞but␈α
the␈α
paper␈α∞with␈α
which␈α
I␈α∞am␈α
most
␈↓ ↓H␈↓familiar␈α
is␈α
the␈α
one␈α
in␈α
which␈α
he␈α
discussed␈α
how␈αto␈α
extend␈α
≡rst␈α
order␈α
logic␈α
so␈α
as␈α
to␈α
include␈αScott's
␈↓ ↓H␈↓theory␈α⊃of␈α∩computable␈α⊃functions.␈α⊃ This␈α∩is␈α⊃a␈α⊃di≠cult␈α∩and␈α⊃important␈α⊃problem␈α∩for␈α⊃mathematical
␈↓ ↓H␈↓theory␈α
of␈α∞computation,␈α
and␈α∞I␈α
don't␈α∞think␈α
Igarashi␈α
completely␈α∞solved␈α
it,␈α∞but␈α
his␈α∞paper␈α
represents
␈↓ ↓H␈↓the only progress so far published.

␈↓ ↓H␈↓        I hope this belated letter will help in making your decision.


␈↓ ↓H␈↓Sincerely,



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