theorem Th2: :: BORSUK_4:5

for f, g being Function
for a being set st f is one-to-one & g is one-to-one & (dom f) /\ (dom g) = {a} & (rng f) /\ (rng g) = {(f . a)} & f . a = g . a holds
(f +* g) " = (f ") +* (g ")