a procedural model of language understanding terry winograd in schank and colby, eds., computer...
TRANSCRIPT
A Procedural Model ofLanguage Understanding
Terry Winogradin Schank and Colby, eds., Computer Models
of Thought and Language, Freeman, 1973발표자 : 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 i
nterpret what is coming
Introduction
• This Paper describes – an attempt to explore the interconnection between the d
ifferent 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 proce
dures• 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
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 , Support 등• Concepts
– Block , Blue 등• Proper name of individual objects
and events– B1, Table2, Event27 등
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
• 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
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 : selectionHorizontal 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 group
으로 구분– Semantic analysis : “the” 의 대상이 되는 o
bject 를 database 에서 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