for D being non empty set
for F, G being BinOp of D st F is commutative & F is associative & F is having_a_unity & F is having_an_inverseOp & G = F * ((id D),(the_inverseOp_wrt F)) holds
for d1, d2, d3, d4 being Element of D holds F . ((G . (d1,d2)),(G . (d3,d4))) = G . ((F . (d1,d3)),(F . (d2,d4)))