A1: {|G|} . [i,j,k] =
{|G|} . i,j,k
by MULTOP_1:def 1
.=
G . i,k
by Def5
;
A2:
o . [i,j,k] = o . i,j,k
by MULTOP_1:def 1;
{|G,G|} . [i,j,k] =
{|G,G|} . i,j,k
by MULTOP_1:def 1
.=
[:(G . j,k),(G . i,j):]
by Def6
;
hence
o . i,j,k is Function of [:(G . j,k),(G . i,j):],(G . i,k)
by A2, A1, PBOOLE:def 18; verum