%log term : highlevel.
(* 
%log counters : highlevel.
%log timers : highlevel.
%log sel : highlevel.
*)

(* predicates

loc : type
cargo :  type
plane : type

cargoAt : cargo -> loc -> prop
planeAt : plane -> loc -> prop
aboard : cargo -> plane -> prop
hasFuel,noFuel : plane -> prop
gasAvail : loc -> prop
*)

(* axioms *)

load : (O) (L) (P) 
       cargoAt(O,L)
       -o planeAt(P,L)
       -o (aboard(O,P) * planeAt(P,L)).

unload : (O) (L) (P) 
	 planeAt(P,L)
	 -o aboard(O,P)
	 -o (cargoAt(O,L) * planeAt(P,L)).

fly : (P) (L1) (L2) 
      planeAt(P,L1)
      -o hasFuel(P)
      -o (noFuel(P) * planeAt(P,L2)).

refuel : (L) (P)
	  planeAt(P,L)
       -o noFuel(P)
       -o gasAvail(L)
       -o (hasFuel(P) * planeAt(P,L) * gasAvail(L)).


(* Tests *)

%  can load cargo into a plane
%prove cargoAt(O1,NY) 
       -o planeAt(P747,NY)	
       -o aboard(O1,P747) * #.

% can move refuel and then move cargo
(* 
   O1 : cargo, O2: cargo, P747 : plane, NY : loc, SF : loc
*)
%prove cargoAt(O1,NY)
       -o cargoAt(O2,NY)
       -o planeAt(P747, NY)
       -o gasAvail(NY)
       -o noFuel(P747)
       -o (cargoAt(O1,LA) * cargoAt(O2, LA) * planeAt(P747, LA) * noFuel(P747) * gasAvail(NY)).