let i1, i2 be BinOp of (Segm n); ( ( for k, l being Element of Segm n holds i1 . (k,l) = (k + l) mod n ) & ( for k, l being Element of Segm n holds i2 . (k,l) = (k + l) mod n ) implies i1 = i2 )
assume that
A3:
for k, l being Element of Segm n holds i1 . (k,l) = (k + l) mod n
and
A4:
for k, l being Element of Segm n holds i2 . (k,l) = (k + l) mod n
; i1 = i2
for k, l being Element of Segm n holds i1 . (k,l) = i2 . (k,l)
hence
i1 = i2
by BINOP_1:2; verum