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CATEGORIES:Microsoft Research Cambridge\, public talks
SUMMARY:Logic programming beyond Prolog - Maarten van Emde
n\, University of Victoria\, Canada
DTSTART;TZID=Europe/London:20141009T140000
DTEND;TZID=Europe/London:20141009T150000
UID:TALK53854AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/53854
DESCRIPTION:A program in pure Prolog is an executable specific
ation. For example\, Quicksort in Prolog is a log
ical formula\, yet shows creditable performance on
long lists. But such executable specifications a
re a compromise: the logic is compromised by algor
ithmic considerations\, yet only indirectly execut
able via an abstract machine.\n\nThis talk introdu
ces relational programming\, a method that solves
the difficulty with Prolog programming by a separa
tion of concerns. It requires writing three texts
: (1) Axioms\, a logical formula that specifies th
e problem and is not compromised by algorithmic co
nsiderations\, (2) Theorem\, a logical formula tha
t expresses the algorithm\, and (3) Code\, a trans
cription of Theorem to C++. Correctness of Code re
lies on the logical justification of Theorem by Ax
ioms and on a \nfaithful transcription of Theorem
to C++.\n\nSorting is an example where relational
programming has the advantage of a higher degree o
f abstractness: the data to be sorted can be any C
++ data type that satisfies the axioms of linear o
rder\, while the Prolog version is limited to the
Herbrand universe. Another advantage of relational
programs is that they can be shown to have a mode
l-theoretic and fixpoint semantics equivalent to e
ach other and analogous to those of pure Prolog pr
ograms.\n
LOCATION:Auditorium\, Microsoft Research Ltd\, 21 Station R
oad\, Cambridge\, CB1 2FB
CONTACT:Microsoft Research Cambridge Talks Admins
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