3 Mar 2004
CS 3243 - Chapter 8
12
Existential quantification
n$<variables> <sentence>
n
nSomeone at NUS is smart:
n$x At(x,NUS) Ù Smart(x)
n
n$x P is true in a model m iff P is true with x being some possible object in the model
n
nRoughly speaking, equivalent to the disjunction of instantiations of P
¡ At(KingJohn,NUS) Ù Smart(KingJohn)
¡Ú At(Richard,NUS) Ù Smart(Richard)
¡Ú At(NUS,NUS) Ù Smart(NUS)
¡Ú ...