
Chapter 12: Performance Evaluation of Logic Programs 441
The
Methods
We shall use the same example for most of the methods. The intensional
database and query are:
Rl ancestor(X,Y) :- parent(X,Z),ancestor(Z,Y).
R2 ancestor(X,Y) :- parent(X,Y).
R3 query(X) :- ancestor(aa,X).
The extensional database is:
parent(a,aa).
parent(a,ab).
parent(aa,aaa).
parent(aa,aab).
parent(aaa,aaaa).
parent(c,ca).
The material in this section is taken from Bancilhon and Ramakrishnan
[1986],
and the reader should refer to it for detailed definitions (although we
now present a few important definitions). A rule in the intensional database is
range restricted if ever ...