1 | 28. ||v2||+1 = ||v||+1  29. i: . i < ||v||+1  [u2 / v2][i] term_types(ds;da;de;[u / v][i]) 30. ||v2||+1 = ||v1||+1 & ( i: . i < ||v1||+1  [u2 / v2][i] term_types(ds;da;de;[u1 / v1][i])) 31. i: . i < ||v||+1  [[[u / v][i]]] e1 s1 a tr = [[[u1 / v1][i]]] e1 s1 s2 a tr [[[u2 / v2][i]]] rho 32. i:  33. i < ||v|| 34. [u2 / v2][(i+1)] term_types(ds;da;de;[u / v][(i+1)]) v2[i] term_types(ds;da;de;v[i]) |