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

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 , 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

• 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 내부적으로 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 : 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

Limitations of the Approach

• Not dealing with all the implications of viewing language as a process of communication between two intelligent