% File 'airport-domain'

:- macros 
  disjoint(#1,#2) -> (-((#1)=(#2)) & -at(#1,#2) & -at(#2,#1)).

:- sorts
  object >> region; 
  mode.

:- variables
  X,Y,Z                    :: object;
  U,V                      :: region;
  M                        :: mode.
   
:- objects
  i, car, desk             :: object;
  home, airport, county    :: region;
  walking, driving         :: mode.

:- constants
  at(object,object)        :: inertialFluent;
  walkable(region), 
  drivable(region)         :: boolean;
  go(object,mode)          :: exogenousAction.

exogenous walkable(U), drivable(U). 

% Properties of at

caused  at(X,Z) if at(X,Y) & at(Y,Z).
caused -at(X,Z) if at(X,Y) & disjoint(Y,Z).
caused -at(X,X).

% Effects of actions

go(X,M)       causes at(i,X).
go(X,driving) causes at(car,X).

% Action preconditions

nonexecutable go(X,M) if at(i,X).

nonexecutable go(X,driving) if -at(i,car).

nonexecutable go(X,walking)
    if -[\/U | walkable(U) & at(i,U) & at(X,U)].
                            
nonexecutable go(X,driving)
    if -[\/U | drivable(U) & at(i,U) & at(X,U)].
                            
% Restrictions on the concurrent execution of actions

nonexecutable go(X,walking), go(Y,driving).

nonexecutable go(X,M), -go(Y,M) if at(X,Y) & -at(i,Y).

% Sizes of objects

constraint -at(car,desk).

constraint walkable(home). 
constraint -walkable(county).

constraint -drivable(home). 
constraint drivable(county).