parent(x,y)->pere(x,y);
parent(x,y)->mere(x,y);

fils(x,y)->parent(y,x) sexe(x,ma);

filles(x,y)->parent(y,x) sexe(x,fe);

frere(x,y)-> 
	parent(z,x)
	fils(y,z)!
	val(eql(x,y),0);

soeur(x,y)-> parent(z,x)
	     filles(y,z);

grande_p(x,y)->parent(x,z)
	       parent(z,y);

oncle(x,y)->parent(x,z)
	    frere(z,y);

tante(x,y)->parent(z,x)
	    soeur(z,y);

cousin(x,y)->oncle(x,z)
	     fils(y,z);
cousin(x,y)->tante(x,z)
	     fils(y,z);

grand_parent(x,y)->parent(x,z)
		parent(z,y);

ancencre(x,y)-> parent(x,y);
ancencre(x,y)-> parent(x,z)
		ancentre(z,y);