Knowledge Representation

Reference: Chapter 13 of Allen
Aim:
To outline a representation of the facts conveyed by NL text, based on first-order predicate calculus, and to describe how quantifiers can be avoided in this notation by replacing existentially quantified variables by Skolem constants and Skolem functions, and then assuming all remaining variables are universally quantified.
Keywords: KB, knowledge base, knowledge representation, knowledge representation language, KRL, Skolem functions, skolemization
Plan:
  • Knowledge Representation Languages
  • Representing quantification in a KRL
  • Free variables for "forall"
  • Skolem constants and Skolem functions for "exists"


Knowledge Representation Languages


13.2 A Representation based on FOPC


Representation based on FOPC 2


Free Variables Can Be Used to Handle "forall"


Skolem Constants and Functions Can Handle "exists"


Skolem Constants and Functions Can Handle "exists" 2


Summary: Knowledge Representation
A taste of knowledge representation has been presented, with emphasis on the use of Skolem functions and constants

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Copyright (C) Bill Wilson, 2003, except where another source is acknowledged.