411 REFERENCE · Wikibooks
Prolog/Inference Engines
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
This article needs attention from experts!
By default Prolog does a top-down logic inference.
Example:
clever(joe).
handsome(joe).
hasgirlfriend(X):-
clever(X),handsome(X).
We run this as "hasgirlfriend(X)." to get the people who have a girlfriend.
Bi-directional inference:
clever(joe).
handsome(joe).
rule([handsome(joe),clever(joe)],(hasgirlfriend(joe))).
run:- call(rule(X,Y)),findall(A,(member(A,X),call(A)),L),
length(X,Rulelength),
length(L,Rulelength),
assert(Y),print(Y).
We run this as "run.".
We don't have to directly ask who has a girlfriend, it gives us all results that can be implied. The benefit of bidirectional inferencing is the speed gain.