(defparameter *grammar*
  '((sentence -> (noun-phrase verb-phrase))
    (noun-phrase -> (Article Adj* Noun PP*) (Name) (Pronoun))
    (verb-phrase -> (Verb noun-phrase PP*))
    (PP* -> () (PP PP*))
    (Adj* -> () (Adj Adj*))
    (PP -> (Prep noun-phrase))
    (Prep -> to in by with on)
    (Adj -> big little blue green adiabatic)
    (Article -> the a)
    (Name -> Pat Kim Lee Terry Robin)
    (Noun -> man ball woman table)
    (Verb -> hit took saw liked)
    (Pronoun -> he she it these those that)))