Decision Game

% Author:
% Date: 11/15/2015

/* animal identification game.

    start with ?- go.     */

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

/* hypotheses to be tested */
hypothesize( frog ) :- frog , !.
hypothesize( caecilian  ) :- caecilian , !.
hypothesize( snake ) :- snake , !.
hypothesize( alligator ) :- alligator , !.
hypothesize(cheetah)   :- cheetah, !.
hypothesize(tiger)     :- tiger, !.
hypothesize(giraffe)   :- giraffe, !.
hypothesize(zebra)     :- zebra, !.
hypothesize(ostrich)   :- ostrich, !.
hypothesize(penguin)   :- penguin, !.
hypothesize(albatross) :- albatross, !.
hypothesize(hilsha)     :- hilsha , !.
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).
hilsha    :- fish,
         verify( lives_in_sea ),
         verify( lays_eggs_in_river ).
snake     :- reptile,
         verify( lay_their_egg_on_land ),
         verify( three_chambered_heart ),
         verify( have_no_leg ).
alligator :- reptile,
         verify( lay_their_egg_on_land ),
         verify(  four_chambered_heart ).
frog :- amphibians,
    verify( lay_eggs_in_clusters ),
        verify( has_slimy_skin ).
caecilian :- amphibians,
         verify( live_hidden_in_the_ground ),
         verify( has_smoother_skins ),
         verify( has_limited_vision ).

/* classification rules */
reptile :- verify(  walked_in_the_chest ) , !.
reptile :- verify( cold_blooded ).
amphibians :- verify( breathe_through_skins ) , !.
amphibians :- verify( hibernate_during_cold_winter ).
fish  :- verify( has_gill ) , !.
fish  :- verify( has_post_anal_tail).
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.