anchor.diff:    (let* ((fig-3-56  '(:concatenation (:closure (:union a b)) a b b))
            (fig-3-63 (make-fa '((0 b 0) (0 a 1) (1 a 1) (1 b 2) (2 a 1) (2 b 3)
                                 (3 a 1) (3 b 0))
  -                            0 3))
  +                            0 (finite-set 3)))
            (my-fig-3-36 (regex->nfa fig-3-56))
            (my-fig-3-63 (nfa->dfa my-fig-3-36)))
   
  
positive.code:                                (q5 1 q6)
                                 (q6 :epsilon q5) (q6 :epsilon q8)
                                 (q8 :epsilon q10))
                               'q9 'q10))
          (regex-2-15-a '(:closure 1))
          (regex-2-15-b '(:concatenation 0 (:closure 1)))
          (regex-2-15-c '(:union (:concatenation 0 (:closure 1)) 1)))
  
negative.code:   (let ((fig-2-15-a (make-fa '((q7 :epsilon q5) (q7 :epsilon q8)
                                 (q5 1 q6)
                                 (q6 :epsilon q5) (q6 :epsilon q8))
                               'q7 (finite-set 'q8)))
          (fig-2-15-b (make-fa '((q3 0 q4)
                                 (q4 :epsilon q7)
                                 (q7 :epsilon q5) (q7 :epsilon q8)
                                 (q5 1 q6)
                                 (q6 :epsilon q5) (q6 :epsilon q8))
                               'q3 (finite-set 'q8)))
          (fig-2-15-c (make-fa '((q9 :epsilon q1) (q9 :epsilon q3)
                                 (q1 1 q2)
                                 (q2 :epsilon q10)
  