/*

  Lewis Carroll's symbolic logic problem #60 in Picat.

  From
  http://www.yesfine.com/carroll_symbolic_logic.htm
  """
  60
  (1) The only animals in this house are cats;
  (2) Every animal is suitable for a pet, that loves to gaze at the moon;
  (3) When I detest an animal, I avoid it;
  (4) No animals are carnivorous, unless they prowl at night;
  (5) No cat fails to kill mice;
  (6) No animals ever take to me, except what are in this house;
  (7) Kangaroos are not suitable for pets;
  (8) None but carnivora kill mice;
  (9) I detest animals that do not take to me;
  (10) Animals, that prowl at night, always love to gaze at the moon. 
  """
  
  From 
  http://www.yesfine.com/carroll_symbolic_logic_simplified_statements.htm
  """
  Univ. "animals"; 
  a = avoided by me; 
  b = carnivora; 
  c = cats; 
  d = detested by me;   
  e = in this house; 
  h = kangaroos; 
  k = killing mice; 
  l = loving to gaze at the moon; 
  m = prowling at night; 
  n = suitable for pets, 
  r = taking to me. 
  """

  Also, see 
  http://stackoverflow.com/questions/15733986/solving-symbolic-logic-with-prolog
  for a Prolog solution.

  Model created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import util.

main => time(go).


go ?=>
   avoid(A),
   writeln(a=A),
   fail.

go => true.

% This index is needed
index(-)
animal(cat) => writeln($animal(cat)),true.
animal(kangaroo) => writeln($animal(kangaroo)),true.

prowl_at_night(cat) => writeln($prowl_at_night(cat)),true.

carnivore(A) => writeln($carnivore(A)),prowl_at_night(A).

loves_moongazing(A) => writeln($loves_moongazing(A)), prowl_at_night(A).

animals_in_house(cat) => writeln($animals_in_house(cat)),  true.

suitable_pet(A) =>
    writeln($suitable_pet(A)),
    animal(A),
    A != kangaroo,
    loves_moongazing(A).

can_kill_mice(cat) ?=> writeln($can_kill_mice(cat)),true.
can_kill_mice(A) => writeln($can_kill_mice(A)),carnivore(A).

take_to_me(A) => writeln($take_to_me(A)),animals_in_house(A).

detest(A) => writeln($detest(A)),not take_to_me(A).

avoid(A) => writeln($avoid(A)), animal(A), detest(A).