theorem Th1: :: MULTOP_1:1

for D being non empty set
for X, Y, Z being set
for f1, f2 being Function of [:X,Y,Z:],D st ( for x, y, z being object st x in X & y in Y & z in Z holds
f1 . [x,y,z] = f2 . [x,y,z] ) holds
f1 = f2