Upper bounds for fusion processes in collisions of weakly bound nuclei
  We obtain upper limits for the contributions of the incomplete fusion and sequential complete fusion processes to the total fusion cross section. Through those upper bounds we find that these processes are negligible in reactions induced by projectiles such as $^{6}$He and $^{11}$Li, which break up into neutrons and one fragment containing the full projectile charge. 
L.F. Canto, R. Donangelo, H.D. Marta