Subversion Repositories programming

mother(charles,elizabeth).
father(charles,phillip).
mother(andrew,elizabeth).
father(andrew,phillip).
mother(edward,elizabeth).
father(edward,phillip).
mother(william,diana).
father(william,charles).
mother(harry,diana).
father(harry,charles).
mother(elizabeth,elizabeth_tqm).
father(elizabeth,george).

grandfather(X,Y) :- father(X,Z),father(Z,Y).
grandfather(X,Y) :- mother(X,Z),father(Z,Y).