anchor.diff:      (:sequence :start-anchor acronym :end-anchor))
   
   (cl-ppcre:define-parse-tree-synonym apostrophe
  -    (:sequence alpha (:greedy-repetition 1 NIL (:sequence "'" alpha))))
  +    (:sequence (:greedy-repetition 1 NIL alpha)
  +	       (:sequence "'" alpha)))
   
   (cl-ppcre:define-parse-tree-synonym apostrophe-word
       (:sequence :start-anchor apostrophe :end-anchor))
  
positive.code: 				  str
  				  "")
        (if (cl-ppcre:scan *apostrophe-word-regexp* str)
  	  (cl-ppcre:regex-replace-all *apostrophe-word-regexp*
  				      str
  				      "")
  	  str)))
  
negative.code: 
  
  (defparameter *dot-regexp* (cl-ppcre:create-scanner '(:sequence ".")))
  (defparameter *apostrophe-s-regexp* (cl-ppcre:create-scanner '(:sequence "'" (:char-class #\s #\S))))
  
  (defmethod normalize ((self standard-tokenizer) str)
    (if (cl-ppcre:scan *acronym-word-regexp* str)
  