anchor.diff:  (defmethod add-activation ((self rete) activation)
     (trace-enable-activation activation)
     (add-activation
  -   (context-strategy (activation-rule activation)) activation))
  +   (context-strategy (rule-context (activation-rule activation))) activation))
   
   (defmethod disable-activation ((self rete) activation)
     (when (eligible-p activation)
  
positive.code: ;;; File: rete.lisp
  ;;; Description: Class representing the inference engine itself.
  
  ;;; $Id: rete.lisp,v 1.38 2002/11/19 19:41:14 youngde Exp $
  
  (in-package "LISA")
  
  
negative.code: 
  (defun reset-focus-stack (rete)
    (setf (rete-focus-stack rete)
      (list (find-context rete :initial-context))))
  
  (defun set-initial-state (rete)
    (forget-all-facts rete)
  