theorem
   [.a,b,c|^ a.]  * [.c,a,b|^ c.]  * [.b,c,a|^ b.] = 1_G
proof
  [.a,b,c|^ a.] = [.b,a",c.]|^ a & [.c,a,b|^ c.] = [.a,c",b.]|^ c &
  [.b,c,a|^ b.] = [.c,b",a.]|^b by Th7;
  hence thesis by GROUP_5:46;
end;
