parent(cyrill, renaud). parent(cyrill, claire). parent(renaud, clovis). parent(valentin, olivier). parent(claire, olivier). parent(renaud, claudia). parent(claire, gaelle). ancetre(X, Y) <-- parent(X, Y). ancetre(X, Y) <-- parent(Z, Y), ancetre(X, Z). cousin(X, Y) <-- parent(Z, X), parent(Z, Y). cousin(X, Y) <-- parent(A, X), parent(B, Y), cousin(A, B).