>
> Is this also useful for implementing something like Datalog? If yes,
> in what ways?
>
> Regards,
> Shantanu
I don't know for Datalog but for Prolog.
Imagine you have
parent(a,b).
parent(b,c).
ancestor(X,Y) :- parent(X,Z) , ancestor(Z,Y). (1)
ancestor(X,Y) :- parent(X,Y). (2)
Now you have the goal:
ancestor(a,V).
to apply the rule (1) you must unify ancestor(a,V) with ancestor(X,Y).
It gives you : {X -> a; V ->Y}
Then, you must unify parent(X,Z) with either parent(a,b) or parent(b,c).
Only the first one is possible knowing X->a and you get back:
{X->A,V->Y, Z->b}...
and so on.
Prolog alternates branching point with an unification of the goal and
the result of the rules....
(and of course backtracking)
Hopes that helps a bit,
Nicolas.
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