Negation
Prolog provides the built-in predicate not/1 which
expresses a form of negation. not(G) is true if
Prolog cannot prove G as true given the current
knowledge base. When the Prolog interpreter encounters a goal of
the form not(G), it tries to prove the goal
G. If G can be proved, then
not(G) will fail, otherwise not(G)
succeeds.
Add a predicate not_parent/2 to the knowledge base of the exercise about family
relationships. not_parent(X,Y) should be true
if X is not a parent of Y.
Solution
Write down a Prolog clause representing that Harry likes all
magical creatures except for dementors.
Hint
Go on here.