Knowledge Systems Laboratory, Stanford
University
20
KBs,
Sentences, Terms
uKnowledge
Base Collection of
sentences
uSentence Expression denoting a
statement
8Logical constant: true 8 Individual variable: ?tv
8Relational sentence 8 Conjunction
(Dad Richard Earl) (and (Dad
Richard Earl) (Mom Richard
Polly))
8Implication 8 Disjunction
(=> (Dad ?p
?d) (Parent ?p ?d)) (or (Dad Richard Earl) (Dad
Richard Alfred))
8Equation 8 Logical
equivalence
(= (Dad
Richard) Earl) (<=> (Dad ?p
?d) (Father ?p ?d))
8Inequality 8 Universally
quantified sentence
(/= (Dad
Richard) Fred) (forall
?p (Parent ?p
(Dad ?p)))
8Negation 8 Existentially
quantified sentence
(not (Dad
Richard Fred)) (exists ?d
(=> (Person ?p) (Dad ?p ?d)))
uTerm Expression denoting an
object
8Object constant: Fred 8 Individual variable: ?The-First-Murderer
8Function term: (Father
Richard)
8If logical term 8 Cond logical
term
(if (Dad Richard Earl) 1 2) (cond
((Person Joe) P) ((Cat Joe) C))