theorem
  for M be Matrix of len b1,len b2,K holds 
  rank Mx2Tran(M,b1,b2) = the_rank_of M
proof
  let M be Matrix of len b1,len b2,K;
  thus rank Mx2Tran(M,b1,b2) = the_rank_of AutMt(Mx2Tran(M,b1,b2),b1,b2) by
Th48
    .= the_rank_of M by Th36;
end;
