“…We define a new nonlocal variable w by T t = w x , T x =− w t . Taking the similarity variables T r = w s , T s =− w r , so that the conservation law is written as where ( , ) and The components T x , T t depend upon ( x , t , v , v (1) , v (2) ,…, v ( q −1) ), which means that T s , T r depend upon for solutions invariant under X . Therefore, in the new case divergence condition, D r T r + D s T s =0 becomes or equivalently …”