theorem Th14: :: RANDOM_3:14

for Omega1, Omega2 being non empty set
for S1 being SigmaField of Omega1
for S2 being SigmaField of Omega2
for P being Probability of S1
for F being random_variable of S1,S2
for y being set st y in S2 holds
(probability (F,P)) . y = P . (F " y)