====== Fam grandparents ====== {{tag>family}} ===== Description ===== A more efficient version of grandparent **Source**: The Art of Prolog ===== Download ===== Program source code: {{fam_grandparents.pl}} ===== Listing ===== /* grandparent(X,Z) :- X is the grandparent of Z. */ grandparent(X,Z) :- nonvar(X), parent(X,Y), parent(Y,Z). grandparent(X,Z) :- nonvar(Z), parent(Y,Z), parent(X,Y). % Program 10.3 A more efficient version of grandparent ===== Comments =====