theorem Th5:
  card (i ';' j)= 2
proof
  thus card (i ';' j) = card (Load i ';' Load j) by SCMPDS_4:def 4
    .=card (Load i)+card (Load j) by AFINSQ_1:17
    .=1+card(Load j) by COMPOS_1:54
    .=1+1 by COMPOS_1:54
    .=2;
end;
