2 | 31. ( i: . i < ||v||  [[v[i]]] e1 s1 a tr = [[v1[i]]] e1 s1 s2 a tr [[v2[i]]] rho)
& ( i: . i < ||v1||  v2[i] term_types(ds;da;de;v1[i]))
& ( i: . i < ||v||  v2[i] term_types(ds;da;de;v[i])) list_accum(x,t.x([[t]] e1 s1 a tr);f([[u]] e1 s1 a tr);v)  list_accum(x,t.x([[t]] e1 s1 s2 a tr);f([[u1]] e1 s1 s2 a tr);v1) |