theorem
  G1 is_transformable_to G2 implies q(#)(idt id B) = q
proof
  assume
A1: G1 is_transformable_to G2;
  then
A2: G1*(id B) is_transformable_to G2*(id B) by Th10;
  thus q(#)(idt id B) = (q*(id B))`*`(idt (G1*id B)) by Th19
    .= q*id B by A2,FUNCTOR2:5
    .= q by A1,Th21;
end;
