Page 163 - DCAP310_INTRODUCTION_TO_ARTIFICIAL_INTELLIGENCE_AND_EXPERT_SYSTEMS

Unit 8: Structured Representation of Knowledge

(* STRUCTURAL DESCRIPTION OF THE WALK FRAME *) Notes
(TDN: [(WALK P A)
((AGENT I FN) PERSON)
(LOC LOCATION)
((TOLOC I FN) LOCATION)
(FROMLOC LOCATION)
((OPPORTUNITY L) (PROPOSITION ((X AGENT) LOC (X FROMLOC))))
(PGOAL (PROPOSITION ((X AGENT) LOC (X TOLOC))))
((PRESUPPOSITIONS L) PROPOSITION)
((RESULTS L) PROPOSITION) ])

(* CONSISTENCY CONDITIONS FOR THE WALK FRAME *)
(QSCC: [((LOCATION Z) | (NOT [X TOLOC Z]) (X (AGENT LOC) Z)) WALK
FROMLOC])
(QSCC: [((LOCATION L) | (X TOLOC L) (NOT [X FROMLOC L])) WALK
TOLOC])
(QSCC: [((LOCATION L) | (X FROMLOC L)) WALK LOC])
(QSCC: [((PERSON P) | (X (LOC LOCOF) P)) WALK AGENT])
The final segment of the example above lists what are referred to as consistency conditions; in
this case for the WALK FRAME. These are expressions that are given a logical interpretation and
constrain the way in which a WALK instance can be instantiated. Note that at the end of each of
these lines the name WALK and a relation or slot are shown in bold. For example, the first is
WALK FROMLOC. This constraint expression is attached to this slot. For example, the first
constraint states that the LOCATION Z that is placed in the fromloc slot is a location such that Z
is not the same as the location placed in the toloc slot; and it is the LOCATION that is in the slot
loc that is associated with the PERSON P in the agent slot of WALK. More simply put; when you
walk you must change location and the starting location of the Walk is the same as where you
are when you begin this action.

!
Caution Use a better programming paradigm for knowledge representation.

Task List out the three level of knowledge representation.

Self Assessment

State whether the following statements are true or false:
9. The expansion history of a particular case can not be represented as a syntactic tree structure.
10. A frame is a data-structure for representing a stereotyped situation.

8.6 Conceptual Dependency Theory and Object-oriented
Programming

8.6.1 Conceptual Dependency Theory

Conceptual dependency theory is a model of natural language understanding used in artificial
intelligence systems. Roger Schank at Stanford University introduced the model in 1969, in the
early days of artificial intelligence. This model was extensively used by Schank’s students at
Yale University such as Robert Wilensky, Wendy Lehnert, and Janet Kolodner.

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