Add exercise 4.45

2023-11-23 22:47:06 +00:00 · 2023-11-23 22:47:06 +00:00 · cb17f567b8
parent 78bfc38b81
commit cb17f567b8
1 changed files with 153 additions and 0 deletions
--- a/mceval/amb-natural-language.rkt
+++ b/mceval/amb-natural-language.rkt
@ -0,0 +1,153 @@
+(define nouns '(noun student professor cat class))
+
+(define verbs '(verb studies lectures eats sleeps))
+
+(define articles '(article the a))
+
+;; output of parse
+'(sentence (noun-phrase (article the) (noun cat))
+           (verb eats))
+
+(define (parse-sentence)
+  (list 'sentence
+         (parse-noun-phrase)
+         (parse-word verbs)))
+
+(define (parse-noun-phrase)
+  (list 'noun-phrase
+        (parse-word articles)
+        (parse-word nouns)))
+
+(define (parse-word word-list)
+  (require (not (null? *unparsed*)))
+  (require (memq (car *unparsed*) (cdr word-list)))
+  (let ((found-word (car *unparsed*)))
+    (set! *unparsed* (cdr *unparsed*))
+    (list (car word-list) found-word)))
+
+(define *unparsed* '())
+
+(define (parse input)
+  (set! *unparsed* input)
+  (let ((sent (parse-sentence)))
+    (require (null? *unparsed*))
+    sent))
+
+
+;: (parse '(the cat eats))
+;; output of parse
+'(sentence (noun-phrase (article the) (noun cat)) (verb eats))
+
+(define prepositions '(prep for to in by with))
+
+(define (parse-prepositional-phrase)
+  (list 'prep-phrase
+        (parse-word prepositions)
+        (parse-noun-phrase)))
+
+(define (parse-sentence)
+  (list 'sentence
+         (parse-noun-phrase)
+         (parse-verb-phrase)))
+
+(define (parse-verb-phrase)
+  (define (maybe-extend verb-phrase)
+    (amb verb-phrase
+         (maybe-extend (list 'verb-phrase
+                             verb-phrase
+                             (parse-prepositional-phrase)))))
+  (maybe-extend (parse-word verbs)))
+
+(define (parse-simple-noun-phrase)
+  (list 'simple-noun-phrase
+        (parse-word articles)
+        (parse-word nouns)))
+
+(define (parse-noun-phrase)
+  (define (maybe-extend noun-phrase)
+    (amb noun-phrase
+         (maybe-extend (list 'noun-phrase
+                             noun-phrase
+                             (parse-prepositional-phrase)))))
+  (maybe-extend (parse-simple-noun-phrase)))
+
+
+;; Exercise 4.45: Output of (parse '(the professor lectures to the student in the class with the cat))
+
+(sentence
+ (simple-noun-phrase (article the) (noun professor))
+ (verb-phrase
+  (verb-phrase
+   (verb-phrase (verb lectures)
+                (prep-phrase (prep to)
+                             (simple-noun-phrase (article the) (noun student))))
+   (prep-phrase (prep in) (simple-noun-phrase (article the) (noun class))))
+  (prep-phrase (prep with) (simple-noun-phrase (article the) (noun cat)))))
+
+;; The cat is with the professor.  The professor is in the class
+;; lecturing the student.  The student may be elsewhere.
+
+
+(sentence
+ (simple-noun-phrase (article the) (noun professor))
+ (verb-phrase
+  (verb-phrase
+   (verb lectures)
+   (prep-phrase (prep to)
+                (simple-noun-phrase (article the) (noun student))))
+  (prep-phrase (prep in)
+               (noun-phrase (simple-noun-phrase (article the) (noun class))
+                            (prep-phrase (prep with)
+                                         (simple-noun-phrase (article the) (noun cat)))))))
+
+;; The cat is in the class in which the professor is lecturing the student
+
+
+(sentence
+ (simple-noun-phrase (article the) (noun professor))
+ (verb-phrase
+  (verb-phrase
+   (verb lectures)
+   (prep-phrase (prep to)
+                (noun-phrase (simple-noun-phrase (article the) (noun student))
+                             (prep-phrase (prep in)
+                                          (simple-noun-phrase (article the)
+                                                              (noun class))))))
+  (prep-phrase (prep with)
+               (simple-noun-phrase (article the) (noun cat)))))
+
+;; The student is in the class.  The professor is with the cat and is
+;; lecturing to the student.  The professor and cat may or may not be
+;; in the class.
+
+
+(sentence
+ (simple-noun-phrase (article the) (noun professor))
+ (verb-phrase
+  (verb lectures)
+  (prep-phrase (prep to)
+               (noun-phrase
+                (noun-phrase (simple-noun-phrase (article the) (noun student))
+                             (prep-phrase (prep in)
+                                          (simple-noun-phrase (article the) (noun class))))
+                (prep-phrase (prep with)
+                             (simple-noun-phrase (article the) (noun cat)))))))
+
+;; The professor is lecturing the student.  The student is in the
+;; class with the cat.
+
+
+(sentence
+ (simple-noun-phrase (article the) (noun professor))
+ (verb-phrase (verb lectures)
+              (prep-phrase (prep to)
+                           (noun-phrase (simple-noun-phrase (article the) (noun student))
+                                        (prep-phrase (prep in)
+                                                     (noun-phrase
+                                                      (simple-noun-phrase (article the)
+                                                                          (noun class))
+                                                      (prep-phrase (prep with)
+                                                                   (simple-noun-phrase
+                                                                    (article the)
+                                                                    (noun cat)))))))))
+;; The professor lectures to the student, who is in the class with the cat