00100	PROBLEMS OF NATURAL LANGUAGE UNDERSTANDING IN TELETYPED INTERVIEW DIALOGUES.
00150	
00200	
00300	     By `natural language` I shall mean everyday American English
00400	such as is used by readers of this book in ordinary conversations.
00500	It is still difficult to be explicit about the processes which
00600	enable hummans to interpret and respond to natural language.
00700	Philosophers, linguists and psychologists have speculated about
00800	and investigated natural language with various purposes and few
00900	useful results.  Now attempts are being made in artificial intelligence to write        
01000	algorithims which `understand' what is being expressed in natural
01100	language utterances.
01200	     During the 1960's when machine processing of natural language
01300	was dominated by syntactic considerations, it became clear that
01400	this approach was insufficient.  The current view is that to unDerstand
01600	what utterances say, knowledGe about linguistic syntax and semantics
01700	must be combined with knowledge about an underlying conceptual
01800	structure containing a world-model and an ability to draw inferences.
01900	How to achieve this combination efficiently represents a huge task for
02000	both theory and implementation.
02100	     Since the behavior  being simulated by  our paranoid model is the
02200	linguistic-conceptual behavior of paranoid patients in a psychiatric
02300	interview, the model must have some  ability to process and respond to
02400	natural language input in a manner indicating the underlying pathological
02500	
02600	to develop a method for understanding everyday Englisg sufficient
02700	for the model to behave conversationally in a paranoid way in a
02800	circumscribed situation.  What is said in this situation is far
02900	icher than what is said in conversations with a block-stacking
02950	i2900
03000	robot but its requirements for constructing an interpretation
03100	of an input are not as complex as trying to understand anything
03200	said in English BY anybody in any dialogue situation.
03300	WE TOOK A PRAGMATIC APPROACH WHICH CONSIDERED "UNDERSTANDING"
03400	TO REPRESENT "GETTING THE MESSAGE" OF  AN UTTERANCE BY
03500	GLEANING SOME {NOT ALL} OF THE RELATIONS BETWEEN THEM.
03600	THIS STRAIGHTFORWARD APPROACH TO A COMPLEX PROBLEM HAS ITS
03700	DRAWBACKS, AS WILL BE SHOWN, BUT WE WERE STRIVING FOR A
03800	SUFFICIENCY TO DEMONSTRATE PARANOIA RATHER THAN COMPLETE
03900	COMPREHENSION OF ENGLISH.
04000	     LINGUISTIC APPROACHES  CITE TRADTIONAL PROBLEMS WITH
04100	AMBIGUITY, AS ILLUSTRATED IN THE FOLLOWING EXAMPLE FROM
04200	WILKS {  }.  SUPPOSE I WALKED UP TO YOU, A STRANGER, ON
04300	THE STREET ON SUNDAY MORNING AND SAID
04400	     {1} `HE FELL WHILE GETTING TO THE BALL'.
04500	ADMITTEDLY THIS IS A STRANGE SCENE AND IN THIS SITUATION
04600	YOU WOULD THINK ME TO BE CRAZY, HUNGOVER AND MAYBE STILL
04700	DRUNK.  BUT THE EXAMPLE IS NO MORE WEIRD THAN THE ISOLATED
04800	EXAMPLES DISCUSSED IN THE LINGUISTICS LITERATURE.  SUPPOSE
04900	FURTHER THAT IN YOUR PERSONAL `DICTIONARY' THE WORD  `BALL'
05000	HAS AT LEAST TWO SENSES, {A} A SPHERICAL PHYSICAL OBJECT
05100	USED IN A GAME, AND {B} A FORMAL DANCE.  {IT PROBABLY HAS
05200	ALSO A THIRD SENSE AS A VERB BUT WE WILL IGNORE THIS MORE 
05300	OR LESS RECENT EXAMPLE OF SEMANTIC SHIFT}.  HAVING NO
05400	FURTHER INFORMATION IN THIS SITUATION AND ATTEMPTING TO
05500	CONSTRUCT AN INTERPRETATION OF MY UTTERANCE, YOU WOULD BE
05600	PUZZLED AS TO WHETHER I WAS REFERRING TO A BALL GAME OR A
05700	DANCE.  IF WE THEN CONTINUED ON OUR RESPECTIVE WAYS, SAYING
05800	NOTHING ELSE, YOUR PUZZLEMENT WOULD CONTINUE AND EVEN INCREASE
05900	--I DON'T KNOW WHAT HE WAS REFERRING TO NOR WHY HE EVEN SAID
06000	THAT TO ME.
06100	
06200	     THE AMBIGUITY ARISES BECAUSE OF THE TWO WORD SENSES FOR
06300	BALL EACH OF WHICH WOULD GIVE THE UTTERANCE A MEANINGFUL
06400	INTERPRETATION.  BUT THE EXAMPLE IS EXTREMELY FORCED AND
06500	ARTIFICIAL.  SUCH ISOLATED UTTERANCES CANNOT BE DISAMBIGUATED
06600	{UNIQUEATED IS A BETTER TERM} BUT THIS IS NO HANDICAP FOR
06700	ORDINARY HUMAN CONVERSATIONS IN WHICH AMBIGUITIES HARDLY ARISE
06800	AT ALL.  BBESIDES THE UTTERANCE ITSELF, EXTRA INFORMATION IS
06900	USUALLY AVAILABLE IN THE FORM OF CONTEXTUAL AND SITUATIONAL
07000	KNOWLEDGE.  EVEN BETTER, ONE CAN ALWAYS ASK.  IF I HAD SAID
07100	ONLY UTTERANCE {1} TO YOU, YOU COULD SIMPLY ASK:
07200	
07300	               {2} `WHAT DO YOU MEAN?'
07400	
07500	AND MY REPLY WOULD INDICATE SOMETHING ABOUT A GAME OR A
07600	DANCE OR WHO 'HE' WAS.