Simple expert system - Animal

gistfile1.txt

% -*- mode: Prolog  -*-
% (c) J. R. Fisher.
% http://www.csupomona.edu/~jrfisher/www/prolog_tutorial/2_17.html 

% Animal identification rules
% To run, type      go.

go :- hypothesize(Animal), 
       write('I guess that the animal is: '), 
       write(Animal), nl, undo.

 /* hypotheses to be tested */ 
hypothesize(cheetah) :- cheetah, !. 
hypothesize(tiger) :- tiger, !. 
hypothesize(giraffe) :- giraffe, !. 
hypothesize(zebra) :- zebra, !. 
hypothesize(ostrich) :- ostrich, !. 
hypothesize(penguin) :- penguin, !. 
hypothesize(albatross) :- albatross, !. 
hypothesize(unknown). /* no diagnosis */ 

/* animal identification rules */ 
cheetah :- mammal, carnivore, 
                verify(has_tawny_color), 
                verify(has_dark_spots). 
tiger :- mammal, carnivore, 
            verify(has_tawny_color), 
            verify(has_black_stripes). 
giraffe :- ungulate, 
               verify(has_long_neck), 
               verify(has_long_legs). 
zebra :- ungulate, 
             verify(has_black_stripes). 
ostrich :- bird, 
               verify(does_not_fly), 
               verify(has_long_neck). 
penguin :- bird, 
                 verify(does_not_fly), 
                 verify(swims), 
                 verify(is_black_and_white). 
albatross :- bird, 
                   verify(appears_in_story_Ancient_Mariner), 
                   verify(flys_well). 
/* classification rules */ 
mammal :- verify(has_hair), !. 
mammal :- verify(gives_milk). 
bird :- verify(has_feathers), !. 
bird :- verify(flys), 
           verify(lays_eggs). 
carnivore :- verify(eats_meat), !. 
carnivore :- verify(has_pointed_teeth), 
                    verify(has_claws), 
                    verify(has_forward_eyes). 
ungulate :- mammal, verify(has_hooves), !. 
ungulate :- mammal, verify(chews_cud). 
/* how to ask questions */ 
ask(Question) :- 
        write('Does the animal have the following attribute: '), 
        write(Question), write('? '), 
         read(Response), nl, 
         ( (Response == yes ; Response == y) 
         -> assert(yes(Question)) ; 
         assert(no(Question)), fail). 
:- dynamic yes/1,no/1. 
/* How to verify something */ 
verify(S) :- (yes(S) -> true ; (no(S) -> fail ; ask(S))). 
/* undo all yes/no assertions */ 
undo :- retract(yes(_)),fail. 
undo :- retract(no(_)),fail. 
undo. 

Você está usando o GNU-Prolog ou o SWI-Prolog? @hwarlley