Run-time Assertion/Deletion of Clauses

• Memoization

  p(X):-
         body(X).
  p(X):-
         body1(X),
         body2(X).
  ----------------------------------
  p(X):-
         body(X),
         assert(p(X)).
  p(X):-
         body1(X),
         assert(p(X):-body2(X)).

• Global counters

  inc_counter:-
         counter(X),
         X1 is X + 1,
         retract(counter(X)),
         assert(counter(X1)).