reserve X,Y for set;
reserve Z for non empty set;

theorem Th12:
  for C1 being non empty AltGraph, C2,C3 being non empty reflexive
AltGraph, F being feasible FunctorStr over C1,C2, G being FunctorStr over C2,C3
  st F is bijective & G is bijective holds G*F is bijective
by Th11,Th10;
