Information Technology Reference
In-Depth Information
Hint:
You will not be able to use the
descendant
predicate you defined for this.
Use the
child
predicate together with
write_child
. Also, work down from
y
rather than up from
x
.
In case you were wondering, these questions do not exhaust the varieties of cousins
people have considered. Anthropologists distinguish between
parallel
and
cross
first
cousins, according to whether or not the two parents who are siblings are of the same
sex. And once the idea of people being
married
is included, there are new possibilities:
step-siblings (children of the spouse of a parent who are not siblings) and siblings-in-
law in two varieties (a sibling of a spouse and the spouse of a sibling). This lead to
step first cousins and two varieties of first cousins-in-law. And so on.
