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weak slot and filler structures

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					                                                                    It supports property inheritance along isa
                                                                       and instance links.
         Structured knowledge
                                                                    In this knowledge is structured as set of
            Representation                                             entities and their attributes.




     Weak Slot-and-Filler Structures
                                                                           Weak Filler Structures
                                                                    • Semantic nets
Index assertions by the entities they describe. Hence retrieveing   • Frames
the result of an entity is fast.


Make it easy to describe properties of relations.


Are a form of object-oriented programming. Hence have modularity

and ease of viewing by people.


Support both monotonic and Nonmonotonic inference.




                                                                                                                 1
                   A Semantic Network                                              Representing Nonbinary Predicates
                                                                                 Unary Predicates can be rewritten as binary ones.
 Information is represented as set of nodes connected to each other by
 a set of labeled arcs,which represent relationship among nodes.
                                                                              could be rewritten as


                                                                                  N-Place Predicates


                                                                              becomes




Use inheritance to derieve additional relation has-part(Pee-Wee-Reese,Nose)




                                                                                          Some Important Distinctions
                                                                                 First way :
     A Semantic Net Representing a Sentence
                                                                                Second way :                             relations
   “John gave the book to Mary.”                                                                                         hip
                                                                                                              entities



                                                                              The nodes H1 and H2 are new concepts representing John’s and Bills’ Height
                                                                              respectively.Using these facts John’s height increased can be considered
                                                                              easily.
                                                                                Third way :




                                                                                                                                                           2
              Partitioned Semantic Nets
                                                       A Simplified Frame System




a)   The dog bit the mail carrier.
b)   Every dog has bitten a mail carrier.
c)   Every dog in town has bitten the constable.
d)   Every dog has bitten every mail carrier.




     A Simplified Frame System (Cont’d)            A Simplified Frame System (Cont’d)




                                                                                        3
Representing the Class of All         Teams   Representing the Class of All      Teams
              as a Metaclass                           as a Metaclass (Cont’d)




                                              Representing Relationships         among
  Representing Relationships among Classes
                                                          Classes (Cont’d)




                                                                                         4
          Slots as Full – Fledged Objects                                     Representing Slots as Frames, I
We want to be able to represent and use the following properties of slots
(attributes or relations) :
   The classes to which the attribute can be attached.

   Constraints to either the type or the value of the attribute.

   A value that all instances of a class must have by the definition of the
   class.

   A default value for the attribute.

   Rules for inheriting values for the attribute.

   Rules for computing a value separately from inheritance.

   An inverse attribute.

   Whether the slot is single-valued or multivalued.




        Representing Slots as Frames, II                                      Representing Slots as Frames, III




                                                                                                                  5
Representing Slots as Frames, IV          Associating Defaults with Slots




   A Shorthand Notation for                  Representing Slot - Values
   slot-Range Specification
                                   As simple frames :




                                   Using Lambda Notation :




                                                                            6
Tangled Hierarchies-Hierarchies that are not
     tree are called tangled hierarchies       More Tangled Hierarchies




                                                                          7

				
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