Transcript A Procedural Model of Language Understanding Computer Models of Thought and Language,

A Procedural Model of
Language Understanding
Terry Winograd
in Schank and Colby, eds., Computer
Models of Thought and Language,
Freeman, 1973
발표자 : 소길자
Index
•
•
•
•
•
Introduction
The presentation of meaning
Semantic analysis
The role of syntax
Limitations of the Approach
Introduction
• Much of the research on language is
based on an attempt to separate it
into distinct componets
– Ordering of syntactic constitunets
– Define semantic relations
– Model the cognitive structures
Introduction
• 의미를 다루는 시스템들의 한계
– 배탁적으로 하나의 문장만 이해한다.
• 인간의 의미해석
– 전후 문맥을 이해한다.
– We make use of What has gone on to
help interpret what is coming
Introduction
•
This Paper describes
–
–
–
an attempt to explore the interconnection
between the different types of Knowledge
required for language understanding
Ex)
Syntactic knowledge
•
–
–
–
“Arthur wants to see him” : “him” must refer to
someone other than Arthur
Semantic knowledge
Heuristic Knowledge
Knowledge of the world
•
“Sam and Bill wanted to take the girs to the movies,
but they didn’t have any money”
Introduction
• It is folly to think of giving the
program all the knowledge
• our program
– mini-world
– We can give the computer a deep kind
of knowledge
– The world of toy robot with a simple arm
Introduction
• Three domain
– Syntactic parser
– Collection of semantic routine
– Cognitive deductive system
• Exploring the consequences of facts
• Making plans to carry out commands
• Finding the answers to questions
– The main emphasis
• The interaction of the three domains
Introduction
• One of the most useful organizing
principles
– Representation of much of the knowledge as
procedures
• Many other theories of language
– State their rules in a form modelled on the
equations of mathematics or rules of symbolic
logic
• To preserve the simplicity
– Putting the knowledge in the form of program
Sample Dialogue
• Q: Pick up a big red block
• A: OK
The Representation of
Meaning
• A detailed world model
– Describing the current state of blocks
– Describing Its knowledge of procedures
for changing that state and making
deductions about it
Database of simple facts
• Relationships between objects
– Is , Support등
• Concepts
– Block , Blue등
• Proper name of individual objects and
events
– B1, Table2, Event27등
Representations of meaning
• The symbols used in these
expressions represent the
concepts(conceptual categories)
• Concept
– corresponds vaguely to a single
meaning of a word
– The connection is more complex
– Ex) ‘truth’ ,’virtue’ , ‘democracy’
Representations of meaning
• System’s knowledge which involves
the interconnections between the
concepts
– In our model, these are in the form of
procedures
– Ex ) CLEARTOP
• GRASP
• This subgoal structure provides the basis for asking
“why” questions
-Q : why did you put B2 on the table?
-A : To get rid of it
-Q : why did you get rid of it?
-A : To grasp B1
“ A red cube which supports a pyramid”
Semantic Analysis
• 영어 입력문장이 들어오면 이를 해석해야 내
부적으로 프로그램을 생성할 수 있다.
• Definition for “CUBE” ,”CONTAIN”
Semantic Analysis
• Usage
– Q: can the table pick up blocks
– A:No
• Table :INANIMATE
• Pick up : ANIMATE
• Rules are calls to program(OBJECT and
RELATION) which do the appropriate
checks and build semantic structure
• Flexibility is done by having the definition
of every word be a program
Semantic Analysis
• Ex)
– “ a big red block and a little one”
– “one” must trigger a program which
looks into the previous discourse
• It tracks of when in the dialogue
something is mentioned
The Role of Syntax
• In process of semantic interpretation ,
part of the relevant input was the
syntactic structure
• The program contains a parser and
grammar
• “the three big red dogs ate a raw steak”
The Role of Syntax
• For each unit, there is a syntactic
program (written is PROGRAMMAR
language) .
• It will call on other such syntactic
programs (and possibly on itself
recursively)
The Role of Syntax
• Our grammar takes advantage of some of
ideas of Systemic Grammar(Halliday,1971)
–
–
–
–
Features
Functions
Ex) “the three big red dogs”
Features : DETERMINED,
INDEFINITE,PLURAL..etc
– Functions : SUBJECT
Vertical Line : selection
Horizontal Line : logical dependency
• MAJOR : independent sentence
•DECLARATIVE : she went
•IMPERATIVE : go
•INTERROGATIVE : did she go?
• SECONDARY : “the ball which is on the table”
The Role of Syntax
• Syntactic features are basic to
description of semantic rules
• Formalism for describing syntactic
process
– Our grammar is written in a language
which was designed for the purpose,
PROGRAMMAR
Program Organization
• Parsing, semantic analysis, deduction
go on concurrently throughout the
understanding of a sentence
• “ Put the blue pyramid on the block in
the box”
– Parser : “the blue pyramid ”를 Noun
group으로 구분
– Semantic analysis : “the”의 대상이 되는
object를 database에서 검색
Program Organization
• There is a continuing interplay
between the different sorts of
analysis, with the results of one
affecting the others
Limitations of the Approach
• The program does not attempt to
handle hypothetical or counterfactual
statement
– Only accepts a limited range of
declarative information
• It cannot talk about verbal acts
Limitations of the Approach
• Not dealing with all the implications
of viewing language as a process of
communication between two
intelligent