for S, T being non empty Poset
for f1 being Function of S,T
for g1 being Function of T,S
for f2 being Function of (S ~),(T ~)
for g2 being Function of (T ~),(S ~) st f1 = f2 & g1 = g2 holds
( [f1,g1] is Galois iff [g2,f2] is Galois )