anchor.diff:  
   
   
  -(defthm foo
  -  (implies (equal (nth n A
   
   (defthm composition-prog-value-correct
    (implies (and (equal (len p) 3)
  
positive.code:            (equal (pdl-prog-value m p) (cdr (assoc p (get-atomic-programs
                                                        (get-frame m)))))))
  
  (defthm composition-right-length
    (equal (len (rel-compose r1 r2))
           (len r1)))
  
negative.code:   (equal (len (rel-star r)) (len r)))
  
  
  (defthm rel-union-behaves-like-union
   (implies (and (natp n)
             (< n (len A)))
            (iff (member x (nth n (rel-union A B)))
                 (or (member x (nth n A)) (member x (nth n B))))))
  
  (defthm union-prog-value-correct
    (implies (and (equal (len p) 3)
                  (equal (first p) 'union)
                  (natp w)
                  (< w (len (pdl-prog-value m (second p)))))
             (iff (member v (prog-accessible-worlds m w p))
                  (or (member v (prog-accessible-worlds m w (second p)))
                      (member v (prog-accessible-worlds m w (third p)))))))
                  
  ;here
  
  
  
  ;(defun composition-of-single-rel (rel r2)
  