% File 'zoo-test3'

:- sorts
  animal >> (elephant; horse; dog).

:- variables
  SP                           :: species;
  E                            :: elephant;
  HR                           :: horse;
  D                            :: dog.
  
:- objects
  elephantSpecies, 
  horseSpecies,
  dogSpecies                   :: species.

caused sp(E)=elephantSpecies.
constraint sp(ANML)=elephantSpecies ->> [\/E | ANML=E].

caused sp(HR)=horseSpecies.
constraint sp(ANML)=horseSpecies ->> [\/HR | ANML=HR].

caused sp(D)=dogSpecies.
constraint sp(ANML)=dogSpecies ->> [\/D | ANML=D].

default largeSpecies(SP). 
caused -largeSpecies(dogSpecies).


:- objects
  homer                        :: human;
  snoopy                       :: dog.


% Initially Homer was outside, and Snoopy, a dog, was inside the cage, 
% with the gate closed. Is it possible that they switched their
% locations in one step? in two steps?  

:- query 
maxstep :: 1..2;
0: -opened(gateAO),
   loc(pos(homer))=outside,
   loc(pos(snoopy))=cageA;
maxstep: 
   loc(pos(homer))=cageA,
   loc(pos(snoopy))=outside.