/LMAR=0/XLINE=3/FONT#0=BASL30/FONT#1=BASI30/FONT#2=BASB30/FONT#10=BAXM30/FONT#11=ZERO30/FONT#3=STA200/FONT#4=NGB25
␈↓ ↓H␈↓␈↓βS␈↓∧ Department of Computer Science, STANFORD UNIVERSITY, Stanford, California 94305

␈↓ ↓H␈↓∧Telephone 415 497-4430␈↓ 
≥July 31, 1980 




␈↓ ↓H␈↓Professor Dana Scott
␈↓ ↓H␈↓Sub-faculty of Philosophy
␈↓ ↓H␈↓l0 Merton Street
␈↓ ↓H␈↓Oxford University
␈↓ ↓H␈↓Oxford England

␈↓ ↓H␈↓Dear Dana:

␈↓ ↓H␈↓        Some␈αtime␈αin␈αthe␈α60's␈αyou␈αgave␈αa␈αformulation␈αof␈αlist␈αprocessing␈αin␈αthe␈αλ-calculus␈αanalogous
␈↓ ↓H␈↓to␈αLISP.␈α
 I␈αthink␈αI␈α
remember␈αthat␈α
T␈αwas␈α␈↓↓λx_y._x␈↓,␈α
F␈αwas␈α␈↓↓λx_y._y␈↓␈α
and␈αthe␈α
conditional␈αexpression
␈↓ ↓H␈↓␈↓↓if_p_then_a_else_b␈↓␈αwas␈α
␈↓↓p(a)(b)␈↓,␈αbut␈αI␈α
can't␈αremember␈α
or␈αreconstruct␈αhow␈α
lists␈αwere␈α
handled.␈α Do
␈↓ ↓H␈↓you have a copy of the memo or do you remember how you did it?

␈↓ ↓H␈↓        I␈αwould␈αbe␈αinterested␈αin␈αany␈αviews␈αyou␈αmight␈αhave␈αon␈αnon-monotonic␈αreasoning.␈α Enclosed
␈↓ ↓H␈↓is␈αa␈α
reprint␈αof␈α
my␈αpaper␈α
in␈αthe␈α
recent␈αspecial␈α
issue␈αof␈α
␈↓↓Arti≡cial␈αIntelligence␈↓␈α
on␈αthe␈α
subject.␈α Since␈α
I
␈↓ ↓H␈↓wrote␈α∂it,␈α∂I␈α∂have␈α∂been␈α∂trying␈α∂to␈α∂apply␈α∂the␈α⊂ideas␈α∂to␈α∂concepts␈α∂as␈α∂well␈α∂as␈α∂objects.␈α∂ One␈α∂goal␈α⊂is␈α∂to
␈↓ ↓H␈↓formalize␈αthe␈αslogan␈α␈↓↓"Ceteris␈αparibus,␈αde␈αre␈α=␈αde␈αdicto"␈↓,␈αi.e.␈αto␈αexpress␈αin␈αsome␈αlogical␈αlanguage␈αthe
␈↓ ↓H␈↓idea␈α∀that␈α∪the␈α∀distinction␈α∪is␈α∀ordinarily␈α∪unnecessary␈α∀so␈α∪that␈α∀ordinary␈α∪language␈α∀is␈α∀e≠cient␈α∪in
␈↓ ↓H␈↓requiring circumlocution to express it.


␈↓ ↓H␈↓Best regards,



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