Knowledge Representation

Made for CSC411 Winter 2013 at UPEI

Transcript

1. {
   Knowledge  
   Representation
   
   Vimal  Atreya  Ramaka
   

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2. Ñ  Knowledge  is  the  body  of  facts  and  principles.  
   Ñ  Knowledge  can  be  language,  concepts,  
   procedures,  rules,  ideas,  abstractions,  places,  
   customs,  and  so  on.  
   Ñ  Study  of  knowledge  is  called  Epistemology.
   Knowledge
   

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3. Ñ  Deals  with  understanding,  designing  and  
   implementing  ways  of  representing  
   information.
   Knowledge  Representation
   

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4. Ñ  A  Knowledge  Representation  is  not  a  data  
   structure
   Knowledge  Representation
   

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5. Ó  A  multidisciplinary  field  applies  theories  and  
   techniques  from:
   Ô  Logic
   Ô  Ontology
   Ô  Computation
   Knowledge  Representation
   

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6. Ñ  Provides  the  formal  structure  of  and  rules  of  
   inference
   Logic
   

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7. Ñ  Study  of  correct  reasoning
   Ñ  Not  a  particular  language
   Ñ  There  are  many  systems  for  logic
   Logic
   

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8. Ñ  Vocabulary
   Ó  Collection  of  symbols  represented  as  chars,  
   words,  icons  or  even  sounds
   Ñ  Syntax
   Ó  Rules  that  determine  how  symbols  combine  to  
   form  well-­‐‑formed  sentences
   Logic
   

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9. Ñ  Semantics
   Ó  Theory  of  reference  that  determines  how  the  
   constants  and  variables  relate  to  things  in  the  
   universe  of  discourse
   Ñ  Inference
   Ó  rules  that  determine  how  paOerns  are  generated  
   from  others
   Logic
   

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10. Ñ  Defines  the  kinds  of  things  that  exist  in  the  
    application  domain
    Ontology
    

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11. Ñ  Supports  the  applications  that  distinguish  
    knowledge  representation  from  pure  
    philosophy
    Computation
    

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12. Ñ  Implementational
    Ó  Data  structures  such  as  atoms,  pointers,  lists  and  
    other  programming  notations  
    Ñ  Logical
    Ó  symbolic  logic  propositions,  predicates,  
    variables,  quantifiers  and  Boolean  operations  are  
    included.  
    Levels  of  Representation
    

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13. Ñ  Epistemological  
    Ó  defining  concept  types  with  subtypes,  
    inheritance,  and  structuring  relations  
    Ñ  Conceptual
    Ó  defining  concept  types  with  subtypes,  
    inheritance,  and  structuring  relations  .  
    Levels  of  Representation
    

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14. Ñ  A  knowledge  representation  is  a  surrogate
    Ó  Symbols  are  used  to  represent  external  things  
    that  cannot  be  stored  in  a  computer,  i.e.  physical  
    objects,  events,  and  relationships.  Symbols  are  
    surrogates  for  the  external  things.  Symbols  and  
    links  between  them  form  a  model  of  the  external  
    system  that  can  be  manipulated  to  simulate  it  or  
    reason  about  it.
    Principles  of  Representation
    

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15. Ñ  A  knowledge  representation  is  a  set  of  
    ontological  commitments
    Ó  Ontology  is  the  study  of  existence.  Thus,  
    ontology  determines  the  categories  of  things  that  
    exist  or  may  exist  in  an  application  domain.  
    Those  categories  set  the  ontological  
    commitments  of  the  application  designer  or  
    knowledge  engineer.
    Principles  of  Representation
    

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16. Ñ  A  knowledge  representation  is  a  fragmentary  
    theory  of  intelligent  reasoning
    Ó  To  support  reasoning  about  modelled  things  in  a  
    domain,  a  knowledge  representation  must  
    describe  their  behaviour  and  interactions.  The  
    description  constitutes  a  theory  of  the  
    application  domain.  It  can  be  stated,  for  instance,  
    as  explicit  axioms  or  compiled  into  computable  
    programs.
    Principles  of  Representation
    

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17. Ñ  A  knowledge  representation  is  a  medium  for  
    efficient  computation
    Ó  Besides  representing  knowledge,  an  Artificial  
    Intelligence  System  must  encode  knowledge  in  a  
    form  that  can  be  processed  efficiently  by  the  
    available  computing  equipment.  Therefore,  
    developments  in  computer  hardware  and  
    programming  theory  have  a  great  influence  on  
    knowledge  representation.
    Principles  of  Representation
    

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18. Ñ  A  knowledge  representation  is  a  medium  for  
    human  expression
    Ó  A  good  knowledge  representation  language  
    should  facilitate  communication  between  the  
    knowledge  engineers  who  manage  knowledge  
    tools  and  the  domain  experts  who  understand  
    the  application  domain.  Domain  experts  should  
    be  able  to  read  and  verify  the  domain  definitions  
    and  rules  wriOen  by  knowledge  engineers.
    Principles  of  Representation
    

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19. Ñ  Knowledge  Representation
    Ó  Logic
    Ó  Ontology
    Ó  Computation
    Ñ  Systems  of  Logic
    Ñ  Levels  of  Representation
    Ñ  Principles  of  Representation
    Overview
    

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