Reference: Chapter 13 of Allen 
Aim: 
To outline a representation of the facts conveyed by NL text, based
on firstorder 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"
