Exercise 4.69: Beginning with the data base and
the rules you formulated in Exercise 4.63, devise a rule for adding
“greats” to a grandson relationship. This should enable the system to deduce
that Irad is the great-grandson of Adam, or that Jabal and Jubal are the
great-great-great-great-great-grandsons of Adam.  (Hint: Represent the fact
about Irad, for example, as ((great grandson) Adam Irad).  Write rules
that determine if a list ends in the word grandson.  Use this to express
a rule that allows one to derive the relationship ((great .  ?rel) ?x
?y), where ?rel is a list ending in grandson.)  Check your rules
on queries such as ((great grandson) ?g ?ggs) and (?relationship
Adam Irad).