A Procedural Model of Language Understanding

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A Procedural Model ofLanguage Understanding

• Terry Winograd
• in Schank and Colby, eds., Computer Models of
  Thought and Language, Freeman, 1973
• ??? ???

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Index

• Introduction
• The presentation of meaning
• Semantic analysis
• The role of syntax
• Limitations of the Approach

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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

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Introduction

• ??? ??? ????? ??
• ????? ??? ??? ????.
• ??? ????
• ?? ??? ????.
• We make use of What has gone on to help interpret
  what is coming

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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 didnt have any money

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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

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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

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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

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Sample Dialogue

• Q Pick up a big red block
• A OK

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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

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Database of simple facts

• Relationships between objects
• Is , Support?
• Concepts
• Block , Blue?
• Proper name of individual objects and events
• B1, Table2, Event27?

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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

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Representations of meaning

• Systems knowledge which involves the
  interconnections between the concepts
• In our model, these are in the form of procedures
• Ex ) CLEARTOP

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• GRASP

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• 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

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• A red cube which supports a pyramid

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Semantic Analysis

• ?? ????? ???? ?? ???? ????? ????? ??? ? ??.
• Definition for CUBE ,CONTAIN

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Semantic Analysis

• Usage
• Q can the table pick up blocks
• ANo
• 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

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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

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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

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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)

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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

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• 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

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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

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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 ? Noun group?? ??
• Semantic analysis the? ??? ?? object?
  database?? ??

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Program Organization

• There is a continuing interplay between the
  different sorts of analysis, with the results of
  one affecting the others

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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

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Limitations of the Approach

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