progenitor(sarah,isaac).
progenitor(abraham,isaac).
progenitor(abraham,ishmael).
progenitor(isaac,esau).
progenitor(isaac,jacob).
progenitor(jacob,jose).
man(isaac).
man(abraham).
man(ishmael).
man(esau).
man(jacob).
man(jose).
woman(sarah).
brother(X,Y):-progenitor(Z,X),progenitor(Z,Y),man(Y).
mother(X,Y):-progenitor(Y,X),woman(Y).
father(X,Y):-progenitor(Y,X),man(Y).
son(X,Y):-father(Y,X);mother(Y,X).
grandson(X,Y):-son(Z,Y),son(X,Z).
grandfather(X,Y):-grandson(Y,X),man(Y).



