probabilitat de la meitat de la esfera

P(r) = ( S(r)/V(r) ) = ( (pi·r^{2})/((4/3)·pi·r^{3}) ) = (3/4)·(1/r)

P(1) = (3/4)

P(3) = (1/4)

P(3/2) = (1/2)

Experiment de txepar a una barrera de cuatre agafats:

Destructor: |xooo| || |ooox|

Constructor: |oxoo| || |ooxo|