let S1, S2 be BinOp of the carrier of F; ( ( for x, y being Element of F holds S1 . (x,y) = the addF of F . (x,((comp F) . y)) ) & ( for x, y being Element of F holds S2 . (x,y) = the addF of F . (x,((comp F) . y)) ) implies S1 = S2 )
assume that
A3:
for x, y being Element of F holds S1 . (x,y) = the addF of F . (x,((comp F) . y))
and
A4:
for x, y being Element of F holds S2 . (x,y) = the addF of F . (x,((comp F) . y))
; S1 = S2
hence
S1 = S2
by FUNCT_2:12; verum