/* ========================================================================= 
   David W. Aha
   8-14-87 (Mom's Birthday)
   An example for EBG

   This is a reproduction of the safe-to-stack domain theory and training
   example as reproduced by Armand Prieditis and Jack Mostow in their  AAAI
   1987 paper on PROLEARN.
   ========================================================================= */

/* Domain Theory */
safe_to_stack(X,Y) :- lighter(X,Y).
safe_to_stack(X,Y) :- not(fragile(Y)).

lighter(X,Y) :-
   weight(X,Weight1),
   weight(Y,Weight2),
   less_than(Weight1,Weight2).

weight(Object,Weight) :-
   volume(Object,Volume),
   density(Object,Density),
   product(Volume,Density,Weight).

weight(Endtable,500) :-
   isa(Endtable,endtable).

/* Training Example. */
on(box1,table1).
volume(box1,10).
isa(box1,box).
isa(table1,endtable).
color(box1,red).
color(table1,blue).
density(box1,10).
product(10,10,100).
less_than(100,500).

/* Query. */
query :- explain_and_store((safe_to_stack(box1,table1)),
                       (safe_to_stack(Box1,Table1))).

query_check :-
  Beforec is cputime,
  Beforeh is heapused,
  safe_to_stack(box1,table1),
  Afterc is cputime,
  Afterh is heapused,
  Diffc is Afterc - Beforec,
  Diffh is Afterh - Beforeh,
  write('Cputime used: '),
  write(Diffc),
  nl,
  write('Heapused: '),
  write(Diffh),
  nl.