(define-lexicon E-0 ()
  ;; Figure 22.5 [p 665]
  "Noun      => stench | breeze | glitter | nothing | wumpus | pit | pits | gold
	        | north | south | east | west"
  "Verb      => is | see | smell | shoot | feel | stinks | go | grab 
		| carry | kill | turn"
  "Adjective => right | left | east | south | back | smelly"
  "Adverb    => here | there | nearby | ahead | right | left 
		| east | south | back"
  "Pronoun   => me | you | I | it"
  "Name      => John | Mary | Boston | Aristotle"
  "Article   => the | a | an"
  "Preposition => to | in | on | near"
  "Conjunction => and | or | but"
  "Digit       => 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9")

(define-grammar E-0 ()
  ;; Figure 22.6 [p 665]
  "S  => NP VP | S Conjunction S"
  "NP => Pronoun | Noun | Article Noun | Digit Digit | NP PP | NP RelClause"
  "VP => Verb | VP NP | VP Adjective | VP PP | VP Adverb"
  "PP => Preposition NP"
  "RelClause => that VP")